I don't think that welding is an issue as long as it is done right. You may want to weld a plate over and/or under the joins in the A. Here is a design that I built that was welded..Actually the A was bent and then plate were welded over the top. The crossbeams that hold the boat are bolted under the frame via U bolts. This allows you to put your sail box inside the frame, not on top.. More clearance for the dolphin striker.