I love my YakAttack Blackpak, but sometimes I want to carry a cooler to keep fish - so I took a 36-qt Igloo Marine Cooler, and added three rod holders to it. I rerouted the cargo-area bungee to secure it to the deck along with some stainless-steel S-hooks.
I drew inspiration from a lot of other cooler mods I saw on this forum as well as the interwebs...
The Hobie heavy-duty cart still fits in the scuppers for transport on-water...the cooler fits perfectly between the wheels.
I have the lid opening towards the seat...if I had it turned the other way, with the rod holders on the hinge side, the lid would bind with the rod holders and not fully open. The lid swings open well-past the 90-degree point, so accessing the cooler from the seat is no issue.