Keep Out Mice!
My '91 sits outside for years at a time as a snug little cabin destination. One concern I had was keeping out the little critters, due to that big crack around the perimeter where top meets bottom.
Never fear! First of course, don't leave food laying out or crumbs or grease either.
But the real solution is Bounce dryer sheets. My dad taught me this as a way to stop mice, rats and squirrels from chewing up automotive under-hood wiring. This works, just weave dryer sheets into the wiring around the engine. The varmints hate that smell, and the wires will stay un-chawed.
So: I applied this experience to my Hi-Lo and stuffed the dryer sheets into the crack all the way around the trailer, from the inside. I also look for holes down low where pipes and wiring come through, such as the bathroom and kitchen, and stuff some in there.
A buddy of mine has a shiny big expensive new trailer parked about 15 yards from mine and he ALWAYS has mice. I've told him about the dryer sheets, but he has not implemented around his slides; he still has the smelly little gray bandits.
While I will not offer y'all a money back guarantee, I can tell you there's not much money to spend to try this out. One box is plenty. If you already have mice, this may not drive them out. Eliminate the unwanted tenants, then protect the trailer with this method to keep them from returning. Good luck and I hope this tip helps someone.