Lots of good comparisons. The two options are very complementary, with strengths and weaknesses lined up on each side. Weighting of factors is key.
Travel pattern is also a big part. I camp at or near trailheads, then go off from there on mountain bike or dirt bike. I carry the bikes on a rack on the back of my 1995 23' Class C rather than towing a trailer. Hide the mountain bike inside when dirt biking since it would cost about 1/4 the whole RV cost to replace it ;)
I move from trailhead to trailhead, boondocking in parking lots or whatever I can find. Scope out potential locations with Google Earth. Seldom use campgrounds, so "stealth" as mentioned by others is important.
One issue is getting across drainage ditches and any rutted road. This is my main disappointment. A 4X4 with toy hauler would probably do much better here. Gray water valve is very low. I will probably replace this assembly so I can turn the valve handle upward.
Also looking at a Load Lifter with onboard compressor to get maybe 5 inches of lift when needed on the back end... plus right/left leveling for the cursed ammonia refrigerator that is such a part of our RV'ing lives ;)
A variant is GF and two mountain bikes. Class C is good for this. I'm glad I did not get a Class B because with two duffels of riding gear, 2 helmets, a couple back packs, tools and parts... either for moto/mountain or two people... gear is stashed in the shower.
Which is OK, but I am continually surprised how little storage space there is in this 7 ton Class C compared to my old pickup with a plywood bunk in the back. I guess that's what toy haulers are all about.