Why would you need a real compressor on-board? Is the idea to be able fix a flat on a 10,000 lb vehicle with dualies at the side of the road? I think I'd just call AAA. If I was real desperate, I might try to get out the spare myself and see if that bottle jack I carry is actually any good for 10,000lbs. But I don't think I'd trust a flat tire plug on such a heavy vehicle, even if I had a compressor that would blow up one of those monster tires.
In fact, I don't even spring for the deluxe AAA membership. Yes, I'll pay more if I actually have to use it, but I also tend toward a skeptical view of insurance in general. I insure for disasters I can't afford, not annoyances that I can.
And I'm still interested in learning what people think is the best small compressor.
Age is another BIG variable...