I agree with calling a rescue group for help. They can help you get it out and might be able to take it and get it a safe place to live. The rescue group can also help if there are kittens.
Don't make loud noises, etc., you'll just freak it out more than it is, and guess what happens when an animal gets really freaked out??? You don't want that residue inside the framing of your RV.
If you can't get help, try a very smelly food (my personal favorite has always been Figaro brand tuna cat food) and set it just outside an opening in the RV. Since it sounds like you're not sure how it got in, you can't really put it where the cat did get in, but if you put it near an opening, the smell will be easier for the cat to sense. And that smell will entice it to come out. And cats aren't stupid - if they want out, they will figure it out even if they got in by accident.