That is one reason I had to leave Nashville, and really one of the reasons I quit playing music professionally altogether in the late '80s. People who've never had to sit through a week's worth of studio, playing root/fifth on I IV V tunes for an endless demo session don't know what they're missing..
When I lived there, I didn't drink or do any drugs but that didn't really influence my gigging either way. Of course, I guess it did since I made it a point to keep it a non-issue.
These days I'm fortunate to play with a few different bands that let me stretch out as much as I like, and are open to fluid arrangements of some pretty cool material. These bands couldn't exist in Nashville unless they played empty rooms for free, or were the kids of country stars. Yes, it is a clique-ish town as you are well aware..
It's funny, a few months ago I was down there visiting my friend JT, and he was lamenting the near-irrelevance of his rack of amps and cabinets (thanks to software) while recognizing the the guitarist and steel players are really the only musicians who get to play whatever they want. So yeah, the Wootens of the world work somewhat outside the system there, and the *kids* and their computers have taken over..
All that said, don't let it get you down and remember that there really is a shortage of musical bassists in the world, and maybe the perfect jam situation will reveal itself to you if you keep your eyes open. As many times as I've given up playing music completely, there's always been something pop up that's been a refreshing opportunity to remember why I have that other side of the brain...
When are you getting that KLR?
John