I was one of the first at Mayo Clinic to have an IIAP (ilium sewn directly to the anal canal with no pouch). When the storage area did not develop as expected, my surgeon had me insert a Foley catheter a couple of times a day and inflate the balloon at the end. The intent was to expand the ilium. This was done at home by myself after my surgeon instructed me by phone. While this helped somewhat, I ultimately had another surgery to create a pouch.
Your situation is different than mine, but still involves stretching part of your anal canal using a balloon apparatus. Trying this before resulting to major surgery (have a GI or CRS do it, not yourself!) would be the way to go. If the procedure works, it could be used again if the stricture returns. You could then ask your doctor if self dilation was a possibility. Here’s hoping that the bougie does the trick.