Mali has just come off spending two months with us out west...going everywhere with us (even walmarts and national parks). She is very familiar with the rv. We are about to leave for 3 months in Florida so she will be ready.
When we left for west we had had her for just 4 weeks...with fingers crossed we took off.
She loves the car and had been trialed in the rv (not sleeping overnight though). She didn't skip a beat. She was mostly quiet (okay except for the first time hearing coyotes and when we were in city of vegas with barking dogs but she did get used to that too).
She goes into her crate voluntarily so it is not punishment. She doesn't get punished. She is a rescue so only positive reinforcement. If we didn't crate her the rare times we go out for a couple hours here and there, we would come home to chewed shoes and not sure what else she would entertain herself with.
I do understand your not using a crate if your dog lived in one; but I do think it is a small price for her to pay (if she is used to rv) and will spend the next couple of months with you enjoying each other and exploring.
Donna