I have a fishing trip coming up and I need to figure out a way of getting my 10' aluminum boat to the lake. I had thought of a couple of 2x4's cut to 48" and some u bolts to attach the 2x4's to the rack but I wasn't sure how well the u blots would hold considering the shape of the side rails .

 

The ubolts will hold fine that's how I mounted my roof rack and never had any issue. The one tip I will give is to run your tie down straps through the cab rather than attaching them to the roof rack. It's gonna be a lot harder for the boat/wind to tip your whole roof off than it is a few tiny little screws!!