I'll tell you what man...

Interestingly enough what you have described is almost exactly how my businesses run.
We have along with our car haul business a transmission and general repair shop both heavy and light duty.
We also do trailer repair and tire sales among other things.
It does take a very substantial amount of time and paper work to run it all but the perks are we get all of our parts,tires and repairs done at very sharp discount as compared to other trucking companies.

 

All the money I’ve spend on repairs on top of what I paid for this truck still wouldn’t buy me a decent newer truck even including the lost time.

 

Ryder sells them.

Doran makes them as does Eaton and other companies.

Easy to find.

I recommend the ones that have temp monitors in them, these are usually the one that gets strapped to the wheel.