If they made a Hopper that worked in an RV, I'd get it.
I also don't see a technical reason why the Wally can't record the four broadcast networks with one tuner as that feed must be picked up by all receivers.
We've been using a Hopper w/Sling in our motorhome for the past four years with no problems, as have many other RV'ers. When Dish says they don't support RV use of a Hopper/DVR, they mean they won't install or maintain one there, not that it won't work. In recent years, I understand that policy has softened though. I've seen Dish service vans in a number of RV parks in the past year or so, usually doing Hopper 3 upgrades apparently.