Cool - sounds like nirvana.
This yak is about 1/5 the weight (20 pounds with oars) and very compact, just larger than a life preserver ring.
But there's an idea - the bait guys around here put a laundry basket into a life ring to keep baitfish. You could find an inflatable life ring and plunk some kind of round tub in there with a lanyard.
I am an avid flats angler and guide and use a Patagonia waterproof backpack or a Sealine high-capacity fold-top backpack, both with belts to relieve pressure on the shoulders.
Good luck with your quest.