leaving dog in RV

Depends entirely on the dog. Some do well, others not. Seems smaller dogs don't do as well as larger dogs, but that is just my opinion from hearing barking from RVs.
How does she do when left alone at home?
If she is crate trained, that is probably the best solution. She probably feels safe an secure there.
If not, take her for a test trip. While you are at your site, leave her in the RV, close the door and blinds, and go outside where she cannot see you and wait. If she starts barking you will know you can't just leave her alone or she will probably bark until you get back. Have heard too many of those from neighboring RVs.
Our Golden just goes into a dark corner in the bedroom and sleeps until we return. Just as she does at home.

Same as the above - we tried the collapsible soft crate and one time the pup collapsed it while we were gone - not sure that was a good afternoon for him. Now we only use the wire crates, bring their beds and toys from home. We only leave them for a couple of hours at a time with the temp set, lights off and TV or radio on.
Honestly, they got so much more wore out camping from endless walks that I think the appreciate the "naps"!

when we started it took the dogs awhile to get comfortable with the camper. ours is stored at home so I was able to let them run in and out when I would stock or work on it. we would have happy hour in the camper on the weekends and they would hang out with us, it took then a little while but once they figured it out they were fine.
the dogs we have now we crate when we leave and also set the temperature so they are comfortable. time to time I will ask a neighbor if the dogs barked, usually the don't- I just want to be a good neighbor.

I would take her along to the Rv when you are preparing for a trip. Or just sit in it for a while in the afternoons... just to get her used to it.

I tried the soft sided crates, and felt that the heat built up in them quicker, I've also seen some where dogs chewed right through the sides of them. I have wire crates that fold down and can be put out of the way when not in use.

When we leave the RV, we make sure the temp is set, we crate the dogs, give them water, close the curtains, and leave the tv on. That way the dogs can't see people outside and the tv muffles outside noises. The aim is so that the dogs dont' bark.

During hot weather, we don't go far or for too long in case something would happen to the electric. The MH can heat up fast on a hot day.

Our dogs were older when we started RV'ing. I wasn't sure how they would do and I was pleasantly surprised. I told my husband, bottom line as long as they are with us, they are happy. They love going.