You don't need to put a Hybrid LNBF on the Trav'ler for the Hopper 3 but you do need to install a DPH42 Switch. Three coax cables have to come from the Trav'ler to the DPH42 switch. One coax from the DPH42 to the Solo Hub. You could put the DPH42 on the roof next to the Trav'ler. I added more coax cables and have the DPH42 inside near the Hopper 3.
The coax in the RV is probably RG6 of reasonable quality. You can re-purpose the existing coax to the TVs but that is probably for the OTA antenna.
If a new RV, then there are probably HDMI cables from the TVs to where the receivers are. In my bedroom cabinet I have the Hopper 3 (HDMI to two TVs) and two Joeys HDMI to a TV.
Someday the wives tales about H3 not in RVs will go away. But the one on DVRs are still rampant.
You will have a better chance of a local installer to implement your system. Dish installers, at least their management, don't want to mess with houses on wheels. You get the same deals from a local installer. I would never buy equipment in the high tech turn of receivers. A two year contract is minor compared to the Trav'ler investment.
Be reasonable, Dish, or the local installer, will want to stick with Dish equipment. When I had the H3 installed, I had a ground tripod dish that I let the installer put a Hybrid LNBF head on then tested out the system with the tripod.
From previous installations of VIP622, VIP722K and Hopper 1 in the trailer I had coax for the Joey connections. So the installer hooked every thing up with the Hopper 3. This was a Dish installer. I connected the switches and the Trav'ler after the installer left. Not bad having a ground tripod as a backup to the Trav'ler anyways.
In my Bounder motorhome, the coax cables from the Trav'ler were routed into the bedroom compartment where the DPH42 Switch, Power Inserter, Solo Hub, and the Hopper 3 and Joeys were installed. I did the install in the Bounder.
Auto-Satellite Install.