Oh hah! My spouse and I did the opposite just a year and a half ago.
I would test every time we took a bathroom break as well as whenever I felt like I was running high or low (luckily I can still feel these, tho). I can't really help with the gastroparesis aspect in regards to suggesting snacks but we took a lot of jerky, cheese (classics!), cut vegetables, quick pick ups (like small boxes of juice), some carb-y bits (rice cakes),trail mix, and nuts.
As far as finding a doctor...eh. I feel like it can be hit or miss honestly? Like a doctor could get super awesome reviews online but in person maybe we don't mesh? I usually google the doctor (most will pop up with medical reviews) and see what comes up. And I try to keep in mind that I'm not tied to this doctor for life and if I feel that we're not a good match after the first visit then it is ok to change. Sorry if that is kind of "well, no crap" kind of advice but it took me a while to feel comfortable doing that in all of our moving.
Good luck! And if you go through Iowa on I80 be sure to stop at the 'Worlds Largest Truck Stop':) - it is kind of ridiculous.