DW stocks the RV in the spring and the food stays there until fall. The cereal is left in the cardboard boxes in closed cabinets. She does bring perishables back into the house between trips.
I didn't see any mention of mouse proofing your RV. I have crawled around under the RV and sealed every opening I could find. I keep mouse traps in the RV but haven't caught a mouse for several years. Haven't seen any signs of mice for years either.
I'm not terribly worried about heat here in the north country. 90s are pretty rare but every few years it might get to 100. Doesn't seem to have had any effect on the food.