What to rent/ Class B, C w/ pass. endorsement for my road test?

I'm confused.

Where am I supposed to find a 16 passenger commercial vehicle to
rent for my road test?

The company I want to work for requires it, and will eventual provide training
for Class A and airbrakes.

Obviously, i'll have to get someone else to rent my vehicle for me, (the hard part)
but I plan on getting both my permit (Class C or B with passenger endorsement) and license next week!

Where should I go?

Thank you for any advice.