In an RV park you’re unlikely to see anything – unless you’re right next to the desert. When its hot snakes stay in heavy brush or the shade of rock piles. If it gets cool in the evening they may lie in a road or blacktop or pavement to absorb the heat. Don’t put your hands or feet – or your dog anywhere you can’t see. And just keep your eyes open and keep the dog on a short leash. Keep in mind they usually, but don’t always, rattle. As said, coyotes are a threat to small animals so don’t let him off the leash or stay outside by himself. It’s extremely unlikely you’d get a snake in an RV. It’s possible, but very unlikely you’d get a scorpion inside. The biggest risk with scorpions would be shoes or stuff you left outside. Shake it out before you bring it in.
AZAmmochief’s and regatijnet1’s comments about valley fever and rodent nests are appropriate, too. But we’re talking about being aware, not concerned. You’ve unlikely to see any of these things. I’ve run across countless rattlers, but I worked and hiked cross country most of my life. And I had a scorpion in my house once that I remember. That’s in 43 years.