I make rice cakes+SIS beta fuel for really long rides 4hrs+. Re rice cakes, the texture seems to go bad pretty quick in the fridge tho. I don't know if you can freeze them.
I am still trying to figure out what my stomach likes and keep experimenting though. A few times this year I almost pulled to the side like Tommy D to take a messy dump.
I like SIS gels and Will give fig bars a try. Maybe that's the answer to my GI issues.