First off I think of the flex sig as scope for lower part of colon. And of course you and I are part of the Ken/Barbie club.
The K-pouch scope enters through the stoma to check the pouch and also part of the small intestine. They take biopsies no matter how it looks--at least in each of my scopes. Observation, confirmed by biopsy can determine whether you have pouchitis. My regular GI doc, in Boston, is extremely capable but he won't do the scope. I have switched to NYC docs because transportation is easier. Otherwise Dr. Dietz would be on my list. Are you able to travel for a scope?
Another thought is importance of frequent evacuation and often irrigation, if not every time. The purpose is to keep everything with nasty bacteria traveling through one's system so it doesn't take up residence as pouchitis. Clearly not medical terminology. I use a large enema bottle, 7.8 oz, as my go to irrigation tool. Lasts for several months and easy to pack in travel bag.
Diet makes a big difference, what diet one latches onto is tailor for their system. Keeping a journal helped me figure it out. Not easy, but glad to have done so. jan