Northwest Fishing Reports

I have been using the Cannon Mini Downriggers on my Sorensen for a few years but recently came in to a deal I couldn't refuse(?) and got two Scotty 1050's.
My question is where and how to mount them? I have the clamp on adaptors but they don't fit the gunnels(not wide enough opening). Also have the 90 degree mounts but not sure if I need backing or not since the downriggers are the 1050's.
I know I can mount them to my aluminum boat with the clamp on pieces but would like to be able to move them back and forth between boats.
As you can guess I'm trying to avoid drilling holes in the boat.
Thanks for any reply.
Rick

I didn't catch how long your Sorensen is but a 2x6 layed gunwale to gunwale at the oarlocks works great. Once in place, drill up through the oarlock to get the right angle. Then through bolt through the board and oarlock. Attach the DR mounts to either end of the 2x6. Easy-peasy

rseas,
Thanks for the reply and the tip.
I can add it to the list of my options. So far it's at the top!
Thanks again
Rick