Hi Ronnie and welcome to the site. I like where you’re going with this. I am all for finding new breads that contain less of the things that can trigger GI symptoms. And it’s likely not just gluten. Breads with less resistant starch, fructans and inulin would also be great. The middle east flat bread mentioned in the book may be one low FP possibility to explore.
Making bread by adding tapioca is also a great idea. The grains table in FTD IBS (now added to FTD Heartburn in the ebook and soon to follow in the print book) lists tapioca but the FP was updated to correct a typo. The GI is actually 81 (not 46 as originally reported) and the FP is only 5 grams for a 1.1 ounce serving!
I can’t find a glycemic index for corn starch (if anyone can find it, please post!), so would try it as more of an experiment once your symptoms are under control.