No. They are obsessively clean. And if you use an absorbent bedding like Carefresh instead of wood chips (wood chips are bad for them for a number of reasons) you would probably never ever smell them.

If you use a wire cage they might make a mess of things by throwing bedding/turds out through the gaps.

But as for your question they aren't smelly animals.

The main issue in an RV would be the high likelihood of serious injury. A hamster would probably get thrown around a bit as you drive as well as having the cage accessories move around and squash him.