Are you talking of the fishing buddy series (110-140). If so check out
https://www.pnwflyfishing.com/forum/index.php?threads/is-there-a-good-way-to-mount-a-fishing-buddy-on-a-pontoon.1218/
if not do you have a photo of your unit?
I use the Scotty clamps (241&242) on my southfork foot rest rail...