Lot of good suggestions and advise but if I only used my RV once or twice a year I would sell it and rent one when needed.
This is especially true if the kids are getting old enough to have schedules of their own and limiting the available camping time.
The easiest would be a class A or C motor coach and toad if necessary. You get the size you need for each trip and you give it back when done.
Locally TT and 5vers are available. I rented a 25 ft. TT for a $1000.00 for 10 days two years ago. I had the TV.
Yes it is expensive and takes some budgeting but you can rent a lot of trips for the cost of the Tow Vehicle you need to properly haul your family and TT.
Good luck with your endeavor.