Just a thought I had after reading the story was, even though the campground provides cable, he could still upgrade the service and get a DVR or HD or cable internet, and then you get a utility bill, for your campground address.
That is what we do, we had too to get our WA licenses and you register to vote when you get your license.
If you have DirecTV you can change your service address and once a year you'll get 3 free months of the movie channels.
It no good that you have to jump through all the hoops, but it is the "new standard" if just about any residency, tax, citizenship issue and be full-time in an RV just adds another layer to the frustration.
We travel nursed for a year and did not spend more than 3 months in any one place, and found out later that for income tax purposes, we had NO state of residency, even though we had Tennessee DLs and had worked mostly in Texas, both states with NO income tax, but because we had no residency, we had to pay a higher federal rate on EVERYTHING.
moral of the story: don't take any part of your residency for granted.