If he's got more work than he can handle, it sounds like you should talk to him about working as his assistant, even if just doing the pick-ups and drop-offs.
No, thanks. I already have a full time job, plus a 53 year old house with 12 acres to take care of.
He is filling a nitch. The local John Deere, Kubota, Exmark, Toro, Stihl dealerships who do service charge more than he does and are always 2+ weeks out on service.