I agree with toedtoes. We stock the TT at the beginning of the season with all the basics and non-perishables. We pretty much keep it plugged in when at home and the refrigerator on from our first trip out until our last. Some things that need refrigeration like condiments, etc we keep in the fridge.
Before going out on a trip, we plan for what our meals will be and shop and stock the perishables. On coming home, we use up any perishables for home meals, but leave everything else in the camper ready to go on the next trip. Things like pancake mix, sugar, creamer, etc. are always in sealed hard plastic containers.
The camper stays in the driveway when not being used and we've not had a problem with insects or mice. Depending on where you live and where you park your trailer (like in a field with tall grass, etc.) you may need to do differently with your foodstuffs.