This rack is three years old. Built it out of 2x4 and painted it black. It is screwed together and it has served me well. The commercial racks have two cross bars. I think they would wear on a set of tubes. This one has eight foot carpeted boards. It is set up high off the bed so the tubes can slide up over the cab and not have so much hanging off the back. I strap the boats together and then x strap the bottom boat to the points inside the bed to keep the rack from moving side to side going down the road. I have hauled cats for many miles like this. Keep the tubes off the cab or they will rub the paint off. If you want some more pictures off this easy to build rack let me know.
If you have an eight foot bed then the rack build gets much easier.
If you start off asking for help, you probably should not even start off.