A bit out of left field, but have you tried her on regumate for the anxiety? I always thought it was for moody, nasty mares, but tried it on my spooky, anxious, but otherwise very sweet mare (regardless of where she was in her cycle) and I couldn’t believe how much more comfortable she was in her own skin. Within three days of starting it, she was much more relaxed in her body - she was so much more comfortable physically under saddle (noticeably less tension) and less reactive/spooky. It just felt like “relief” for her, I guess from a chronic physical discomfort she was living with that just hadn’t appreciated. The difference was palpable to the point where I would think it cruel to take her off of it at this point.
As I read through your posts it seems like regumate might be something easy to try if you think the anxiety might be contributing to the ulcers.
Side note - have you tried melatonin to help her sleep at night? I’ve given mine a few tabs (maybe 15 mg?) in new places to help her settle. I have no idea if it does much but it’s pretty inert stuff as far as side effects go.