Tire tools, jack, support stand or block, wrench, etc. That's if you want the capability to change a flat tire even if your first response would be road service.
I believe everybody should have a DVOM to at least start troubleshooting electrical issues. If you have a meter that can measure Capacitance and AC Amperage, you can do preliminary checks on Air Conditioning.
Chassis-wise, even the Fords are very sophisticated and Sprinter goes way beyond that. So I'd say: Cell Phone, Extended Warranty Card, Road Service Card and CREDIT CARD.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB