In this bananas car and RV market, I am not sure i would suggest out trucking by as wide a margin as possible. Not that it’s bad advice, generally that is what you want to do but this market has prices so high on trucks and RVs that in a year or two, you would likely find yourself underwater on those items unless you were paying cash, but even then it is money that doesn’t correspond to the actual value in normal times.
Most modern 1500/150 series trucks would tow that just fine. In many cases, buying a 3/4 ton truck would be probably make sure you have the right truck for the next RV, but in all likelihood by the time you are getting your next unit, prices on 3/4 ton trucks will have come back down from the stratosphere and those trucks will actually be available to purchase.
So in this market, I would recommend matching your trucks capabilities to your current needs. 2-3 years from now, the used market will be flooded with lightly used RVs that people shouldn’t have bought and trucks will be in supply and prices back to normal.
For a 5,500lb towable that is dry - plus at most, a generous 4,000lbs of carrying capacity - that’s 1500/150 with a towing package territory.