A couple issues:

Dual wheels actually give less traction, espically when off paved roads.

By the time a school bus is for sale to the public its had many many miles on it and needs quite a bit of maintenance.

The flashing lights are disabled and painted over because of legal reasons.

School buses are slow moving, not very manuverable, inefficient and get stuck easily so while they have a lot of room they have a lot of disadvantages as well.

You can live out of conversion vans or a truck camper or a camping trailer as well.

Another issue I see if the daily driver vs. BOV parked in your back yard. I see a lot of people drive the little economy car to work every day with a nice loaded up and ready to go BOV parked at their house. What happens if something happens between your work and home and you have to go the other direction, you have now lost access to your BOV. you also don't want to be driving something like that to work every day. A jeep ir truck can be driven to work daily so your gear is with you.