You could try a Riders International blanket from Dover. I tried some for my ponies and found the neck opening HUGE for them. It was like they just made the blanket smaller but left the neck opening the same as for the horse-size blankets.
They are pretty good blankets, though - they work great on my horse-size horses, but just don't fit my ponies.
I'll try and find the page, a gal on facebook is making blankets for ponies. She advertises on the used tack pages.
I can't swear by a price but I think she was advertising a medium weight custom for under $100 and guaranteed it for a year.
Back when my family was into halter horses, we did use some Big D, but usually it was cheaper and more practical to have our local leather guy make us a blanket. In our barn, their are a few older blankets, and still one of the favorites is at 90in with giant padded leather shoulder area outdoor blanket that was made for my moms big halter horse before I was born (pre 80's). The OTTBs can't destroy it for nothing.
"Oh yeah baby, check out the movement of those hind legs"
I'd totally go for a reasonably priced custom!!! There are some made in Sweden for the bizarre icey conformation, but they are like $400!!!! Plus you have to have them shipped, and then they may or may not fit, and then......
The Icelandic lady an hour away from me swears by Weaver and Big D for her Icelandics.
I have an Amigo Hero XL for my draftXmorgan whose neck ties in fairly low and it fits him great both in the neck and shoulders. the 72 is slightly long and hangs off his bum a bit, but i'd rather it hang off the back than be too tight in the chest.
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Saving Pennies To Get My Own Canoe
The neck opening was very big and the shoulders are extra long but adjustable. Way to much shoulder for the Arab that I had bought it for. Oh, also has a very long shoulder gusset which really helps prevent shoulder rubs.