If trolling in the Summer, I do not run umbrellas but instead use tandem rigs with a mixed spread of Storm shads, bucktails, and Tony spoons, or use spreader bars when trolling. During the Spring and Fall when the big rockfish are in, I use a spread including singles, tandems, or umbrellas. I use four arm medium and large size umbrellas with parachute and 9" shad on a 18" to 24" leader with 6" teasers. Some folks run small umbrellas off of their planer boards.
Attach the umbrella directly to the inline weight which is attached to the braid with a coastlock swivel. As the Spring season moves into May you may want to downsize some of the shads from 9" to 6".