Well, I LOVE my Devoucoux Makila for my wide backed monster Shouldered Connemara Pony. He has moderate withers. They also have a new saddle out that I got to try--was really ideal for the horse you are describing.
I wanted a Schleese Wave--but they were not able to fit this pony in that model because he needed a completely different tree with swept back points.
My Wise Equestrian dressage saddle, with a gullet change system, works well on my wide backed, low withered mare. I am very long from hip to knee, as well. The flaps are cut a bit more forward, which helps when you have a long femur.
I have the world's longest femur. I didn't really notice this until the 5'10" girl at the barn said so. So I started lining mine up against peeps. Yup, my femur is akin to those 5'10" - 6' tall and I'm only 5'6".
I always had trouble with saddle "rubbing", now my guess is the two are related. I ride in a L'Apogee and LOVE it. Same saddle Silva Martin uses, btw. It comes in 2 "seats" at each size-regular and "short seat". I have the "short seat" which basically moves the sweet spot where you settle in. No rubs ever (well, that one time Janine Malone made me ride sitting/medium trot for 15 straight minutes at a fix-a-test but that's extreme). It's a monoflap so very close contact, and foam flocked, which I was really skeptical about until Kitty (saddle designer) talked to me about it.
My horse is only a medium wide, but considering he's only 15.2 and 1150 lbs, he's wide proportionately. He does not have "huge" shoulders, but he has a very handy front end and really uses those shoulders and goes really well in this saddle.
I would suggest the Schleese - they have shoulder relief panels to accommodate larger shoulders; extended stirrup bars to accommodate long femurs, wide gullet channels to accommodate a wide-backed horse (with a narrow twist to ensure the rider doesn't feel 'pulled apart' when sitting on this wide-backed horse).
I have your body type and my horse fits your description.
I ride in a Cardinal Cachet, modified with the external 'slanted' block. It looks a lot like the Custom Wolfgang, but it is much nicer imo.
I have never understood the concept of bringing the stirrup bar back for a long thighed rider with a short calf. If I bring the thigh back, there isn't enough length of calf and that results in my calf getting positioned too far back.
I have the most extreme femur to calf ratio out there, coupled with a tilted pelvis. Difficult!
Here's a photo of my saddle that was just refurbished. I like it so well I paid to have new seat and flaps.
I am another shorter person with a very long femur. And I like short coupled horses. And I HATE forward balance saddles (which knocks out some of those lovely French saddles).
So, part of it depends on where you (rider) like the saddle to balance. And what the rest of your build is like. Generally people with smaller butts seem to do better in flatter seats, and larger butts like the more deep scooped seat. But there is variation there too.
You probably need a more forward thigh block (see how much forward angle ToN's picture shows?), and probably will do better with a shorter thigh block so your knees are not trapped.
Then your horse - flat back or curved? Big withers or mutton? Slab sided or round? You say WIDE but HOW wide? Hoop tree wide, or regular ol' wide horse? Long back or short? There is so much more to it then "wide" with big laid back shoulder!
Many of the custom saddle makers can help with different types of back. And there MAY be some good off-the-rack solutions as well. Because my horses have all be short backed, I get short panels on my saddles. So that combo of long leg and short horse means I almost always end up going custom - most of the "off the rack" saddles have long gusseted panels.
What is your budget? Can you afford new and custom? $5k to $8k, gulp... Or are you looking for used, or new, but OTR?
I'd suggest calling a few knowledgeable saddle fitters - where is Jaybird - one of the COTH saddle fitters? Or call Trumble Mountain, they have some really knowledgeable people.
I have a long femur and have churned through many a dressage saddle. Something with a forward flap and if it has a block, a shorter, forward-slanted block like ToN's saddle is the way to go. With the used saddles, I struggled constantly, and the only one that ever worked for me was a County Connection with a forward flap. Eventually ordered a custom saddle with a shortened block and 1.5" more forward than standard. I actually wish I'd gone 2" forward, but it's working for me. The extremely straight cut of most dressage flaps is so frustrating, and the issue is exacerbated if your horse is wide and not huge (making me ride with a touch shorter stirrup so I can actually put my leg on).
I'm not sure about the wide shoulders, but the Black Country I ended up with worked very well on my flat-backed appaloosa (Vinici X which is a hoop tree), and is proving pretty versatile in that it looks like it will work on my new Hanno filly and I'm currently using it on an Azteca mare with a Saddleright pad to fill in some space.
It does sound like your horse is a hoop tree type or a hybrid hoop type. It's difficult without the proper photos. Come saddle companies offer this type tree and some of the ones we work with also have a forward flap option at no extra cost. The front block shape and placement also factors into the mix. Feel free to contact me.
Either Frank Baines or Black Country should be able to accommodate your horse. If his big shoulder is extreme you might want to consider the Harry Dabbs Future Panel which cuts away to give more space to the shoulder.
To give you enough flap for your long leg you might look at GPD saddles made by any of the three companies. The flaps are cut slightly more forward. I, too have a very long thigh and I've found it to be the best option for me.
I too have a femur that is ridiculously long compared to my lower leg - I'm 5'6 1/2" and my horse sounds like yours - monster shoulder, curvy back, and well sprung ribs - a barrel like a barrel. When I ride him toward the mirrors, I look like a little kid with my legs sticking straight out on a Thelwell pony
The saddle that works nicely for us is an Equine Inspired - made by Frank Baines.
But it sounds like you have a lot of options, given the thoughtful responses you have received. Best of luck!