Oomo

I've often wondered how to approach this when sitting down. Standing up, it seems easier to have the bass at the right height for a straighter wrist. Sitting the bass on my knee makes this a lot harder (without raising my elbow and shoulder, which then causes shoulder aches and pains...). I've tried resting on the other leg (classical guitar style), but that just gave me pain in the shoulder of my fretting hand when playing the low positions.