For Pac NW Dungeness, I've used the folding square ones and the riund traps. My buddy claims the round traps are better. Maybe, but last year I put both out and found that they caught about the same amount of crab. Actually the square folder caught a few more. Pots dont need weighed down... even up here in 5-6 knots of current
and up to 100 feet down.
RE: Rod holders. I'm using black plastic ones, these are used sucessfully with 14# downrigger balls and up to 45 lb salmon. Very sturdy. (Cannon, Tempress etc)