-- Last Updated: Mar-30-11 9:57 PM EST --
....... cut a perfect fit hole in the rear deck to accept a 3-1/2 gal. bucket ... they are shorter than a 5 gal. ... the 3-1/2 gal. bucket is 10-3/4" tall and 12" dia. across at the lid .
Most all those type buckets have a rim of some sort around them about 3" down from the top ... so the 3-1/2 gal. would set into the yak about 7-1/2" with the other 3" sticking above deck ... the buckets are about 11" dia. under the rim (that would be the aprox. size of hole to drop bucket into , if you are going to cut , you would have to take the actual , measurement under the rim of what ever bucket you have) .
If you cut the hole the correct size (just 1/16" less in dia. than what the bucket's o.s. dia. is under that rim that is about 3" down from top) ... the bucket should fit very snugly into the hole , you would probably have to give it a twist to pull it out ... plastic to plastic like that makes a snug bond ... you should be able to take the bucket in and out of the yak at will , it's portable if not sealed to the yak .
Anyway , I would want any extra weight to be as close to the bottom of the yak as possible , not on top of it ... even if you filled the intire 3-1/2 gal. bucket with water , that would only be 28 lbs. , and I think any extra weight will serve you better if it's low and behind you (keeping your bow light as possible) .
I could be incorrect but I see the bucket idea with that lid as a good dry rear hatch ... you can organize the interior of the bucket you know with compartments if you wish .
If you look at those lids , you will see that practically the intire interior width of the bucket is accessable ... don't know this for certain but the bucket organizers (stackers , etc.) may pass through the lid w/o any problem .
Here's a link to some bucket organizers , stackers , etc. (the yellow and red plastic things at bottom of page)...
or put parachute bags inside the bucket ...