First of all, pay very little attention to any post that says DON'T or NEVER, SHOULD NOT or similar wording. Rarely is anything related to satellite TV that clear cut.
For what you want to do it sounds like you will be using the satellite service at home more often than you will be using it in your RV so a home installation is EXACTLY (sorry, kidding) what you want to do.
Once you have the home system setup you can simply move the receiver from the house to the RV for you travels. The only slight "got ya" would be if you have DirecTV install a Genie and multiple clients on your other TV's. This system required special antenna hardware (the SWM thing) but even that can be dealt with for about $100. If you want to use a portable automatic antenna then you just want to ensure that DirecTV sets you up with at least one receiver with a model number of H24 or lower so you don't have any issues. If you find that you really like your new Genie (a DVR with 5 separate tuners and very cool!) then it's just a matter of buying the right antenna for your RV and you are, again, ready to go.
Edit: Spelling....