Hello all, I have a 2015 S21 that does not have any board racks or speakers mounted on the tower. What speakers and racks with which adapters work with the built in mounting points on the stock tower? It seems like the rear rack mounting points will support a swivel-type rack. Are the speaker mounts the same as MasterCraft towers? It looks like the Wet Sounds MC-11 adapters might work. I'd like to use the existing mounting points, rather than clamps. Thanks.