You have several concerns, so I will address each one individually. It will all go back to what YOU BOTH think about the situation. If you are not in agreement, being in a limited amount of space will not be good situation for either of you.
1. Money - it is a large amount of $$ to get started because once you purchase the TV, RV, you will need to stock it with supplies. You are doing it the right way by going used, so if you find that you don't like the lifestyle, you can probably re-sell for about what you paid for it and not be out thousands of dollars.
2. Set-up - the first few times you do set-up and take-down, it WILL be hard and take you quite a bit of time. Once you learn your RV and get your list going, you will be able to do it in just a few minutes. (From pull it until completely done, takes us about 20 minutes.) It used to take us over an hour.
3. Being away - did you not say that your 22 year old son still lived at home? At that age, he should be able to handle things for weeks, if not months at a time. Besides, at that age, it might do him good to have the additional responsibility of taking care of a house. (I don't know him, so this is just pure conjecture, but I know my son, at 22 sure could have used some limited responsibility.)
Only the two of you can make the decision to purchase or not, but I will tell you that we LOVE the lifestyle. We are both retired, but have two children, soon to be 10 and 7, so our lifestyle must revolve around school. We did spend 107 nights in our RV last year, so we are working around school pretty well!!
2017 Ford F350 Crew Cab 6.7L 4x4 DRW