What weight 8/0 beast hook would you recommend for slow crawling bottom in 20-30ft with a 6” trash fish and 6” fatty trash fish? Would 3/4oz be overkill because I’d be working it so slowly? 

No, 3/4 is my starting point for 20’+

You're good with 3/4

3/4oz is what I would use for dragging as well. 1/2oz would work too but I would use a stop and start retrieve or pop it off the bottom like a spoon.  The only downside to these techniques is if are you fishing them in a stirred up muddy bottom.  If that's the case, a heavy drop shot is a better choice.