Maybe this will do better:
15 passenger van with wheelchair lift

It can be fitted with a roof rack, a second fuel tank and a few extra lights.

Problem with this type oif vehicle is space under the hood is very limited. A second battery will be great especially if you add a few extra lights for camping or rescue.





It is even longer than the bus but the ground clearance looks better. Also, dual conversions are available for rear wheels if necessary (I like dual wheels for many reasons other than traction, you have instant spares if one tire goes flat).