You should (reconsider) it sounds. The $1800 price tag on the one you linked earlier would more than build what you've drawn. Not to mention when you're constantly ask "nice rig, where'd you get that?"...you can say (with a big smile) "I built it"
Again....way early in the game for me, but I doubt I'd spring for Marine Plywood (since I'd require 2 sheets), just for the fact I'd paint it well, and if it needed replaced after 5 years, it wouldn't be expensive to to, and that's only $10/year. I'd even consider aluminum diamond plate formed like a standing-seam roof (only inverted) to the panel sections could be even smaller (than 2-4'x6' plywood sheets), but that's an added expense I doubt I'd want to bear once I priced it.
I got the drop-in cooler idea from looking at pics yesterday and liked it as well. I think I'd add a toe-catch to keep from bending-over every time I had a fish to toss-in. It would also be easy to add a smaller one with a pump for bait to circulate lake water through it, but again, doubt I'd get that extravagant. I've got a nice aerated bucket that'd work fine.
I just saw the seat(s) on a box as opposed to pedestal in a Post I found in a search: http://www.crappie.com/crappie/kayak...-big-boat.html
It's in the link Blackhawk posted for where he got his pontoon (which is extremely nice). Box would be nice (for jacket, etc), but the less I have mounted, the less would need to come-off when knocking-down, plus keeping weight down.
C'mon....I will if you will