When I had an echelon we ran tube sack in the ski locker, another side sack in the walk through, one fat sack on each side of the engine box. This seemed to maximize seating while still providing a great wake
The boat is narrow 90" beam so it sinks it pretty good. Never used a wedge and never had any complaints. The sacs on the side of the engine were great back rests for anyone wanting a good view.