In Motion Satellite

For in-motion sats there is no HD signal for Directv correct? from what I can tell Dish is only option for HD for in-motion...shame since I have DTV at home.

We take or S&B home receiver with us in the rig. Since it's a DVR we have all of the recorded shows so when trees are blocking the sat we still have the recorded option as well as the OTA optin.

I have the dish 322 dual tuner receiver for different viewing. It's not HD though.

Did you get proof that your new-to-you King Dome system is in good working condition? If not, you may be in for a nightmare.
I bought my StarTrac SV360 in-motion system back when I bought my 2003 Dutch Star. It worked flawlessly up until 2 months ago, and I'm still trying to figure out exactly which of several TracStar "boxes" I need to replace.
BTW I've eliminated the DirecTV receiver from being the problem, it still works fine.

To answer your question, according to DirecTV, there's two ways you can do it. IF you already have DirecTV in your house, they can lease you a small receiver for your RV, cost is $5 per month for this receiver. There are other caveats. If you only want to subscribe for your motorhome, I believe you have to be a fulltimer (live in it all the time).
I don't know about the other vendors.

Moved from Class C.

Oh and if you do all this what happens if the dome doesn't work? That could cause you to wish you had taken a different approach.

And 2 TVs generally means two receivers.

But you might have cabling etc to allow both to use one receiver and both will watch the same station. In that case you may want a receiver with a RF remote so that it will work in either location.

You need to find out if the dish will support two tvs or not. Then you need to figure out which company works with your dish (or both). Then you need to find out which receivers work with the dish. Then you can order it from the company (leased) or Amazon (purchased) or camping world (purchased) - what ever your preference. Then you need to subscribe to a service. Then you hook it up.

You can probably get all these questions answered in your walk through, including those about the xm radio.

BTW It might be in your best interest to either wait until you get home or get local help.

In either event there may be plenty to learn without the entertainment on the way home.

Get the dome model number and look up it's capability. It might only support one vendor or be switchable to several. Then get a receiver possibly directly from DirecTV or Dish. Regardless you will need a subscription for the receiver. Usually the receiver will stay with the owner.

For DTV the receiver is a leased item even if you think you've "purchased it", not sure about Dish. Since satellite is apparently new to you you might consider using a independent satellite installer.

Find the XM receiver and call in the ID for a subscription.