I know of a trucking company with 4 drivers and 2 mechanics...
Sounds like you guys are really moving.
A local place I know of has 5 semi tractors, 6 tandem dump trucks, 2 shooter trucks, 2 small dump trucks, 2 small hoes, a small crusher plant, and 3 loaders. They have a full time "mechanic" and a part time PM guy. Their "mechanic" is good at changing tires, that's about it. They could easily get by with one part time mechanic who actually knew what he was doing. It sounds like a lot of equipment, but there's only 7 or 8 guys working there, so not many hours/miles being put on the equipment.