Not a house boat but we've done both boat and RV.
For similar lifestyle and convenience, it will be at least as expensive, more likely higher cost.
As mentioned, anchoring out gets old real quick unless you like to just sit on the back deck and if you goal is just to go to remote areas to save money, you can boondock in an RV. If you go into marinas, expect a 50-100% increase in your per night cost for equivalent locations.
That said, getting a trailerable houseboat is not a bad idea. Rig it up with stairs and a pump out system so you can use it as either an RV or a boat and you've got a very flexible travel platform.
PS: Trailerable really makes a houseboat a compromise. On a boat, you really want to be able to easily get around to the edges of the boat in order to dock, anchor, etc... but that means you eat into the interior space. A 1ft wide side deck (very marginal) leaves you only just a 6ft wide interior assuming 8ft overall to avoid wide load permits.