Is Part time driving possible?

That will get a class B. Or class A with a 5th wheel restriction if you can find the appropriate trailer. But I still doubt they will rent to an individual. Too much liability.
As for your mechanic buddy. Unless he's with you, and more importantly, owns the truck he cannot legally let you drive it. First it's not his to allow. Second only the Authority owner can allow passengers in a CMV, and they have to have a written permission with the named individual.

I know it may look like I'm trying to discourage you. I'm not. I really do hope you do get your CDL. Thing is it needs to be done legally or else you'll just get into more trouble trying to get it then it's worth for you.

 

Judging by what I see on the road these days, I think there are a lot of “part time drivers”.
It’s what they’re doing as the truck is going down the road that makes me nervous.

 

Would you regale us with some of your more colorful interactions with miscreants and wrong doers?

 

I actually thought about writing a book. Kinda a bucket list thing.

 

Verify it's a class A, but that looks awesome.