This is real similar to what I do to warm up.
He's absolutely right that eventually it just feels natural and you can go almost anywhere with it.
Unfortunately unless you're a huge Rolling Stones fan, there's not a ton of hard rock songs in G major.
After a cursory google, Cracker's "Teen Angst" (what the world needs now [...is a V8 engine]) is the only one I know.
...but it absolutely fits the bill about being easy to run the lead solos for, and the rhythm part feels very natural despite me having kind of a rough start figuring out it was in G the first time I tried to play it.