Adding satalite radio to class A

If you do have to install (no plug) get the relay that disconnects the radio antenna and feeds directly.

If your radio has AUX input the add on radios work great. if you get one be sure it is OK for ala carte service, as it is cheaper and you don't need to fight with them once a year for cost savings.
If your radio doesn't have AUX input the FM receiver will suck whenever you are in/around big cities where there is no station free zones and you get interference.
bumpy

We do the same! We have 2-docking stations (one truck, one TT) and also the portable boom box. we had to purchase the cassette aux tape for the truck if you dont have an aux option. we used the aux jack in the TT stereo. The boom-box will have a seperate antenna and can also be used with AC/12v or 8-D batteries. You will also need a seperate antenna for each dock. We love ours!

Does your radio have a plug in the front to plug in the XM radio? If so you just need to get the XM radio plug it into a dash power port. xm antenna on the dash or put it on the Roof. Plug XM into front of your radio and listen to XM after getting a subscription from XM. OR buy a newer radio for the RV that already has XM install it in RV and subscribe to XM.

Only choice you have is Sirius/XM. The big choices are in the receivers. Some of them qualify for the cheaper Ala Carte subscription, some don't.

I recommend a receiver that can be moved from dock to dock. We have a StarMate5 which sits in a dock in the truck and moves to a dock in the fiver when we are stationary. Not as big an issue with a class A, but you could use the portable receiver in a car as well.