portable Satellite antennas, like yours and mine, work by pushing power back out to the antenna, thru the same coax cable, from the receiver... so typical RV wiring will not handle this 'two way' direction since many RVs have multiple splitters inline to go to other TVs, etc.
Use a direct coax connection and you'll be just fine, as you stated. You'll just have to find a way to bring it into the coach - I use a slider's rubber seal for entrance. Some use a window, and other bring it in thru the roof via a plumbing pipe. Some wetbay areas also provide an entrance option if they already have a wiring/plumbing chase into the interior of the coach.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
110,000+mi since '14 - US, Alaska, Canada (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )b