Fish box:
It is one of those long Tupperware containers for storing bedding. It was over 3' long I believe (you can see it extending under seat in the yellow circle..
First I drilled some holes on the bottom of the box to attach the skirting and used grommets and caulking to make the box water tight again. I drilled enough holes so that the bond between the skirting and the box was near water tight. A little water would get in (maybe an inch) which I found beneficial for keeping my Smelly-Jelly from turning to liquid in the summer. The skirting joined long the bottom and up both side, extended out from under the box and attached to the foot rests using some small inserts I made for the actual rest and the PVC bar you can see is zip-tied to the skirt itself. The skirting is old pontoon material from a toon I blew up at Olalla....
I insulated the box by getting some flat foam insulation sheeting, cutting it size to make a total of five pieces: One large piece for the bottom, and one each for the sides. I used insulation gluing to affix it to the sides of the bin, and then filled in all the gaps with spray foam.
At that point, I used more insulation gluing to cover the interior with space blanket material, making sure to cover the entire surface to be glued in order to support the blanket material as it's very thin.
I then cut part of the lid off and used zip-ties to make a door.
With the lid on I went through and drilled holes through the lid and along the outside lip of the bin and used more zip ties to attach it to the frame (blue circle).
The issue now was running into boulders and breaking the box. So to protect against that I got some metal and bent it into shape to attach to both sides of the frame and extend under the box (red and green circles).
The rod holder is your basic Scotty's holder with the receiver mounted under the metal plate with the female end sitting just below a large hole I bored out of the metal. The metal is covered with skate-board grip tape.
I also used some 1'' aluminum squaring to raise the seat a total of two inches which was GREAT! And yes, my seat is Da Bomb.