Someone previously mentioned skirting around the bottom to help with weather and critters. To help prevent mice and insects from getting in I would crawl all around underneath to find and plug any entry points. Anything the size of a dime will allow mice. To keep red squirrels out of my 5th wheel I used some of the spray insulation foam. But in addition to that I bought some steel wool pads, cut them down to a smaller size and while the foam is fresh I stuffed the steel wool pads into the foam. This keeps the little critters from chewing through the foam, which they will do. Their little teeth don't like the steel wool.