I would think cramming 10 people into a van, then driving said unfamiliar vehicle around unfamiliar roads, would be more stressful than waiting for a bus.
If you decide to go this route I would look at finding one to have who ever is going to drive to try before you head down. there is a big difference in size esp when it comes to parking
Check https://carrentalsavers.com - they have some good discounts built in. Book as far in advance as you can, rental agencies have limited vans. You may consider renting two vehicles, more flexibility plus may end up cheaper. Check your insurance and credit card, certain Vans may not be covered. Good luck!