Somebody has left you with a big job if you want to rectify it properly to last a very long time.
I have not recoated an RV but I have done the hull of a 32' boat.
It is work & the bulk of that work is in the preparation. In my case there was damage to repair first. Then came the sanding. Then came the fairing. Then came the sanding. Then came more fairing. Then came more sanding.
This is where your job comes in, assuming there is no damage to repair. Remove the decals. Underneath will be fresh shiny gelcoat. Wipe the whole rig down with acetone to clean anything off the surface. Sand, sand, & sand some more coming down to a finer grit each time around. Prime coat. Wet sand. Prime coat again. Very fine wet sand.
After all of this preparation it would be criminal to go cheap on the paint. Use a high quality marine epoxy paint such as Aulgrip. At least two coats of that followed by two coats of clearcoat.
The result is going to be a better than new gelcoat finish that will last many years with minimal maintenance.
This is not a job for an amatuer, though if you are somewhat handy with such things you can do some of the time consuming donkey work of the first steps.
Cheap? No way, but well worth the money over the long haul & time saved keeping it looking good retaining the value of your rig.
