Rent plane from another private pilot?

I'm about 15 flight hours along in flight training.
My buddy is about 30 hours along and rounding the bend.

He's going to buy a plane - just part of his overall goal.

So here's a question:

(Let's assume I get a my PPL and checkout in the plane
and everything is cool .. .)

If he owns a plane, can I rent from him?
Or is that considered "commercial" operations?

I would certainly want to get my own insurance.
And I'm sure he'd want to be covered appropriately.

Can anyone help on that matter?
Should we talk to AOPA?

Thanks!