Launch and retrieve the 19' bay boat in signature with our 32' class C. Only time I've ever had an issue is at an RV park/marina on Hilton Head Island. The ramp is 90* off the main entrance driveway with an planter island right in front of the ramp. The island interferes with front end swing of MH. I've done it several times but this year had the jet ski rental guy back trailer down with his jeep for me. I think the pressure of trying to get out of the way of folks coming in driveway adds to difficulty. No problems at several Corp parks on local lakes. I think a 24-26' RV would be much easier to back trailer. As mentioned already, a backup camera with mic is very useful as well as having a second person that will handle either the MH or boat.
The only problem is if towing boat, you will not have a toad. We've not really had an issue with that, just realize we might be limited on where we can drive RV. Also, we keep camp site setup simple to make disconnecting to drive MH quick. I use a brass quick disconnect on city water and only connect sewer when dumping tanks. We don't mount fancy awning lights, etc. either. We keep inside as picked up/tidy so there isn't a lot of stuff to put away. For example, after morning coffee, we rinse out coffee pot and put back in storage cabinet. We have several baskets with non-slip feet on dinette table and galley counter to keep small items in. We can be pulling out of site in about 5 to 10 minutes if we need to go somewhere in MH. We have also learned to live we MH being a little more unlevel than most folks like. That makes it much easier to drive off.