when you are at home let her go into the RV, feed her in the RV from time to time and put her favourite bed in there to, also start the motor a few times when she is near it or in it to get her used to the sound, she will never stop being skittish at her age, but she can adapt given time, she need to realize that the RV is a good place to be, and that is thru food rewards when she goes in and lots of cuddles while in the RV. the motor will freak her out and it will take a lot longer for her to get used to the noise, so you just nead to persavere