Welcome to Mayo Clinic Connect, @cgypsy. It depends on which campus you are visiting.

I do know that Florida has a large parking lot on their campus dedicated to RVs if you will be driving one down and you can park over night there. You may want to contact the concierge desk to see whether or not you would need a parking pass to do so. You can also contact them to find out if there is an RV park nearby at any of the other campus's as well.

Traveling to a new place for medical care can be stressful. Mayo Clinic Concierge Services can help make your trip go smoothly. They provide information about travel, lodging, Mayo Clinic and community resources to plan your visit. And it’s free.
Contact form: http://bit.ly/2nM3mr0
Hours: Monday-Friday, 8 a.m.-6 p.m. CST by phone, 8 a.m.-5 p.m. in person
Location: Mayo Building, Lobby level, International Center
Email: concierge@mayo.edu
Phone: 507-538-8438

@cgypsy, will this be your first visit to Mayo Clinic?