I think it will be difficult, but with patience, you may be able to convince kitty to enjoy RVing life. I would start by getting her used to wearing a harness. With a cat that absolutely hates it, that will take extra effort. Perhaps start by putting it on her when before giving her treats. Let her wear it for a while each day, and hopefully, she'll become less resistant. Also, keep her indoors and only let her go out if she's wearing a harness. If she can associate going outdoors with the harness, she may accept it better. One of our cats was also a great hunter and had some trouble adjusting, but he came to associate the harness with a walk outdoors and would stand patiently while we put it on him so that he could go for his walk each day.
Be sure your cat has plenty of entertaining toys that will also give her some exercise. And don't forget to provide several places to scratch! Cats who are used to being outdoors will miss the activity and the opportunity to scratch and stretch in natural surroundings. We carry at least three different types of scratching pads and posts for our cats, and they use all of them.