For a horse who trailers well and ties well, would it be very difficult for them to adjust to staying in a standing stall once-in-a-blue-moon overnight? My barn has 3 standing stalls which I would like to take down and replace with 2 box stalls, but I wonder if I could "get by" for now as it is, since they will be living outside anyways.
In Europe, many riding centers had rows of standing stalls for their school horses.
Some were fancy with partitions, some had only a log hung up between horses and horses would lay down fine to rest, tied to the mangers.
Very important to have horses that get along with standing stalls, don't want them to be fussing and maybe getting injured.
At times, we moved a school horse to a box stall when we had one open and the horse, if left to choose, would run out of the stall and stand by his standing stall, that was his real "home".
Above all, most horses seem to be creatures of habits and if you train one to certain (sensible) patterns of management, that is what that horse will be happiest with.
Always be sure your horse is comfortable with what you do and if so, all will be fine, standing stall or whatever way you want to manage.
my now-retiree once lived in a straight stall when he was on the hack string many many many moons ago. He loved his cozy stall, as did the other hacks. None of the horses were tied, they walked in and had a row of windows to hang their heads out the other side. Feed pan and water bucket were hung by the "window", solid plywood walls between horses, but they could touch noses (aka play halter tag). Butt chains kept them from backing out. Everyone knew which stalls had mares in them and never made the mistake of loafing by their stalls else you ran the risk of getting peed on.
Many horses were able to lay down and get back up in the straight stall too, they would slide up and down the wall. My gelding used to do this, but he bears the evidence in the form of a capped hock from repeatedly hitting the wall and sliding down, and a permanent shoe boil on the point of his elbow from his front leg being folded underneath him.
The only thing I really hated about the straight stall is that my gelding would laydown in his own pee (barn did not use much shavings back then). In the winter, his wooly mammoth belly would be shaggy with sticky, stinky, frozen pee-cicles, manure bits and shavings. He would end up getting irritated skin even in his girth area, and I would go through a lot of dry shampoo in the winter months.
Be sure none of your horses are small enough to attempt trying to turnaround in the stall. One pony did years ago and got stuck, fortunately someone was on hand and was quickly and easily able to remove the wall partition.
My OTTB (17+h) whom I know had never seen a standing stall in his life (the closest thing was the saddling paddock or a trailer), spent 2 nights in a standing stall in unfamilliar surroundings (with bear roaming nearby). I was a bit worried when I heard that the campground that only offered standing stalls but he was quite happy for the 2 nights.
This is a guy that LOVES his naps and takes his nap schedule quite seriously. He has certain times and depending on the season he has certain places in the pasture. He would be the first eaten by the predator if he were ever turned out in open country. Whenever we are away for the night and he is in a box stall, he will lay down and sleep between 3-5am no matter what is going on around him.
He will stand for hours happily in the trailer but not tied to the outside and I would not hesitate to put him in a standing stall (or even the trailer if there were no other safe accomodations) for 2-3 nights in a row.
I would make box stalls and do not recommend standing stalls. Horses are large animals and they need to move and lay down..years ago they were common now thru education we know they do not benefit from them. I knew a barn that had them and saw horses get hurt.
A barn I massage at has 2 horses from being in standing stalls are now afraid to lay down and have narcolepsy.
I understand sometimes options are limited too..
Just my 2 cents