Try getting her used to just being in the trailer for short periods first. If she likes toys, establish a "camping toys only" stash in the trailer. Have "camping treats only" and keep them on hand in the trailer at all times. Then, bring her in with you while you clean, organize, etc. Every time you go into the trailer, call her to join you. Give her a treat, encourage her to play with her toys.
Try having driveway camp-outs. Feed her in the house at the normal mealtime, then at bedtime, go sleep in the trailer with her. Grab a book and go sit out in the trailer reading; bring out the laptop and surf the web in the trailer; etc. Bring her with you every time. Just let her get used to the trailer as an extension of the house. Then start feeding her in the trailer.
She may always have some nervousness about it, but the more she sees it as "part of our home", the less nervous she'll be when you go camping.
I did this with my two dogs. They transferred from a trailer to a motorhome without a blink of the eye. They love their RV. When it gets home from being at the shop, etc., they get all excited and are at the gate waiting to climb in. Once they get inside, it's straight to the toy box:
