I'm not sure a single flat bar on the outer edge is the way to go. For shedding snow, traction, and strength up and down it is probably fine, but it has little strength side to side. So if you bounce the board off of something, a tool box slides into it in the trailer, or even just pushing the rear of the sled out away from you while you are riding could end up bending them.
The best of both worlds would probably be a triangular extrusion on the edge with one of the points facing up. Not as friendly to make bends in during fabrication though and the traction would probably need to be machined into that edge somehow. Might ice up like some OEM edge grips do? Would also need to find one that had very thick walls like the outer tubes are on existing aftermarket boards. For me the extra rigidity helps with maneuvering the sled and is just as important as snow evacuation or traction.
The best of both worlds would probably be a triangular extrusion on the edge with one of the points facing up. Not as friendly to make bends in during fabrication though and the traction would probably need to be machined into that edge somehow. Might ice up like some OEM edge grips do? Would also need to find one that had very thick walls like the outer tubes are on existing aftermarket boards. For me the extra rigidity helps with maneuvering the sled and is just as important as snow evacuation or traction.