Step 1: Parts List and Tools
-Rod holder, I already had one from my boat, but they run around $17 from Cabela's. If you are really crafty, you can probably build one from PVC
-Dual Suction Cup, the kind for moving glass $8 from Harbor Freight
-U-Bolts size varies by suction cup and rod holder, mine are 1.5"
-old bike tube
Step 2: Construction
I cut a 3" by 3/4" piece out of an old bike tube to prevent the base from sliding around on the suction cup grip. This may not be necessary, but I thought it might help out.
Next I roughly mocked the u-bolts into the holder base to see how much I needed to cut off with the hacksaw. While cutting, I find it easier to screw the nuts beyond where I am cutting so they can re-thread the cut end when they come off after cutting.
Last step is to put it all back together, with the bike tube between the rod holder base and the grip of the suction cup. The u-bolts will "v" a little as they tighten, but be careful not to over do it.
Step 3: Gone Fishing
I was trolling some lead core line, going after rainbows and Kokanee. You don't really feel the added weight or drag of the gear behind you, but the turning radius is affected.
I chose to run the suction cups parallel on the board which I like the best (most of the pics show perpendicular). I also decided to run the rod in front of me for strike indication and ease of removal, I was able to angle it right so it didn't affect my paddling. Overall I like the quality and strength of this project. Good luck!