just go to tractor supply and get the largest water sistern they have...i think its about 1500 gallons....perfectly sealed.....you'll get tossed a bit, but when everything settles, you'll be on top of the water in your own boad...then you can cut the opening open larger and have a nice little boat....plenty of room for all you need....

strap yourself to the floor so you dont get tossed...cheap, efficient and failsafe...