I understand what you are saying about setting up a 2 and 3 LNB dish.
I traveled a lot with the Dish 500. Then switched to Directv with the 3 LNB dish. It can be a pain in the ass setting up these dishes.
I have standard def. tv so I now use a duel feed single LNB dish. I have to run two RG6 wires because with the duel feed LNB each output is different. One feed carries the even transponders and the other carries the odd.
Here is a link to a great, very active forum that you can find any answer about satelite tv. But they are very green about traveling and RVing. http://www.dbstalk.com/
I will try to explain what I do to run 2 sat. feeds into my suite using the standard wiring from the factory.
I have an auto roof dish and also use a tri-pod dish at times. My tri-pod dish setup should work for you with your carryout.
I removed the splitter on the cable feed behind the hookup center. And use the cable and satelite feeds from the hookup center to get two sat. lines to the ent. center. Either way, you have to remove any splitters and put a co-ax connector in place of it.
This may work for you...with the addition of a 12v outlet in the hookup center.
Then I run the two feeds into a multi-switch that combines the even and odd transponders and splits them into four feeds. But I only use 3. Two sat. feeds go to my DVR and one goes to the bedroom.
My satelite wiring is much more complicated than this with the combination of the auto roof dish and the ability to use cable when I am using the roof dish and being able to wire all this through the video selector switch so we can watch the VCR, DVR, cable, or DVD in the bedroom as well as the living room separately. I can watch about anything in any room without manually changing any wires, just pushing buttons on A-B switches and the video selector.
I hope this may help you...