No matter what state we are in, if we are stationary for more than a few days I get out the large gallon jug of Ortho bug stray and go around my fiver. I make sure I put a generous amount around my 6-point level-up legs, shore power cord, water hose, sewer hose, and anything else that goes from the ground to the trailer.
Also, about every 3 or 4 months I buy a couple packs of ant traps (little black plastic ones). I put two or three inside and two or three in my bottom storage areas.
We haven't had anything that crawls inside of our fiver for over 2 years.