You could always just pull a couple of 5 gallon pails alongside the boat. They actually work very well.
I troll with a drift sock, with pretty good results. 90 Horse Evinrude on a 17 1/2 ft Sylvan. I hook the sock on the bow eye. It deploys under the bow of the boat. It stays out of the way up there. Has little effect on boat handling. Slows me down to a nice Walleye troll. I often troll to a spot, then drift. I never have to move the bag. It's working on the drift, as soon as I cut the motor.