This problem varies a lot from state to state. I'm in AZ where tags are based on the MSRP and reduce each year. It's pricey. I paid almost $3700 last year for registration and about the same for insurance. We have no violations or claims, so it's probably just the cost of the RV. Add that up and you're talking over $600 per month for the right to own it and drive it.
I decided that we don't use it enough to justify the cost. I'm not going to give up RVing, but we are downsizing from a 2011 Tour 42QD to a 2015 Holiday Rambler Vacationer. The MSRP is less than half, which makes the expense a lot more tolerable. The new coach suits the way we'll use it and won't drain the checking account...as quickly :)
I'm not one to try to bend the rules and register in another state. I live in AZ so I register it here and bite the bullet. If I registered it elsewhere, I'd probably get caught. I don't want to test those waters.