That's a big chunk of money per month to spend on something you'd only use occasionally. Your kids are young and they will probably be getting into more and more activities - sports/school.
Camping is fun and if you like the atmosphere of campgrounds, there are some that have rental trailers or small cabins right on the site. If you go to national parks, stay in one of their cabins.
Bank that $1200/month to pay for that occasional vacation. You can have just as much fun without a RV and no ongoing payments/repair bills/storage issues, etc.
Memories can be made in many different ways. You don't need to buy a RV to make them.
