Here's what I've been doing-it works. Do NOT park RV near long grass/weeds/trash/water or under trees. Cement pad is the best.
Clean it super-well. In and out. Remove all food,(even cans and bottles), soap, candles, firewood, aerosol cans. Remove all linens/throw rugs/shoes/ clothes-wash them before you put them back. Wipe down all surfaces/inside cupboards. IOW: Remove anything that smells attractive to insects/rodents.
I do use those electronic things that you plug it,(you need to have power to the coach).
I put rubber snakes and rubber toys with BIG eyes under the TT. Sounds funny, but the mice don't know they're fake.
I do check for any holes. I put steel wool inside a plastic bag, (so it doesn't rust/stain), and plug the holes.
If you bait traps with peanut butter, etc. You are just attacking them with the scent of the bait. Poison baits are very dangerous and also have an attractant to get them to take the bait.
So far, so good doing it this way. In the spring- I have a nice. mouse/insect-free TT that doesn't smell like cat pee or moth balls.