I have a ten and a seven inch random orbital polisher. I originally bought them to use the ten inch on the truck and van. I bought the seven inch to use on my fiberglass boat. They help but the down side for me is the wax loading up on the polishing pads and I have to constantly clean the pads off. The van's roof is ribbed so it's useless there but is very helpful on the sides and hood.
The seven inch on the other hand is too small and the pads load up too quickly. The ten inch is really too big for my boat so I just grin and hand polish the boat.
I use a soft paste wax by Meguiars and it is fairly easy to apply and rub off. It's not like the paste wax of yesteryear where you had to have arms of steel!
I use the liquid Mequiars wax for fibreglass boats/RVs, and I do it by hand.
I thought about using an orbital polisher, but worried about peeling a decal off. And it tends to spit polish all over the windows and such, making more work.
It is a heck of a lot of work, but well worth it.