I presume you want a bow mounted post.
How do you spring now? Pontoon - console - pontoon?
Why not run the spring back from the bow eye to the pontoon and then to the A frame or towing eye? The fore line will lie under the tube and not be in the way and the aft line will lie over the tube. Put some pipe lagging, preferably Armaflex, round the rope where it crosses the tube. OK it will be a bit of a sod to attach to the bow, but better than tripping and rubbing.
"A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools" Douglas Adams