How to keep critters out of your RV.

(1) First off plug up all the holes where propane lines, electrical lines, plumbing enter the RV from underneath using the spray foam to fill up the holes. Now something I have used in addition to the expanding foam (used this on my house to keep squirrels away) before the foam dries sprinkle some cayenne pepper on the foam. One taste of that and they will not think about chewing through it.
(2) Peppermint solution spray it around the tires, on the electrical cord, on the hose, anything that touches the ground and could be a place for spiders, ants, just bugs in general, they hate the smell of peppermint. Here is the recipe to make peppermint spray:
     (a) 16/20/32-ounce spray bottle
     (b) Peppermint Oil, I use doTERRA, but you can probably use any.
     (c) Fill bottle up with water, put in some of the oil, I use a 32-ounce bottle and put in about 10 drops.
     (d) Not sure it works, spray it in an area where some bugs are, I have seen spiders literally run/scurry away as soon as I spray somewhere near them.
(3) Fresh Cab bags inside the RV, this is another essential oil-based method that I use, you can find them here:
You will hear people talk about Irish Spring soap and dryer sheets. Here is what I have found, mice eat Irish Spring soap and make nests in your RV with dryer sheets, so I pass on them.