For just 3 days, and if you don't mind tent camping, you might check out renting 2 vans.....with car toppers, they should hold 15 people and 3 days worth of gear. And probably cheaper than an RV that would hold 15. Or drive in your 3 separate cars, rent a small U-Haul trailer to throw all the "stuff" in and save a LOT of money !!
Enjoy
Wendy
Enjoy
Wendy