I cannot believe there is not already a solution installed for this RV.
Before you go any further, see if you can call the manufacturer and see how
this unit was prepped.

What is the make and model?

If this was not prepped for the installation of a satellite dish on the roof, you should probably have him go to an authorized dealer for the install to avoid
future issues. RVs and boats suck to retrofit. many trim panels are glued, or used pin staples to hold it together.

GREAT Advice.

ive serviced several coaches and they can be a bitch depending what you have to do or access. penetrating roof, fishing wires from roof to A/V equipment, etc. falls in the bitch category. definitely find an authorized dealer for him and work with the dealer to get it done.

We have done a few installs not many, most people change there mind when they get the quote. Have used Winegard and KVH.