FOR CHEAP DRYBOX
OK Here is the poop!
I did some research and as usual most people who recommend something don't give the real details or complete details of where to go to get what you are asking for so here is it.
Go to a Target Store or Amazon.com(free shipping) maybe Walmart and look for the Rubbermaid Actionpack
storage box in 24 gallon #1172
is 26.5x19.3x17.4in or the 35 gallon # 1191
is 35x20.8x16.9in . After you buy one go to Homedepot or McMAster Carr
(online) and get some of the holow tube (bulb seal gasket they call it) weather stripping and glue it into the recess on the box. Here is the McMAsterCarr link for the bulb seal. Use the #9 or #10 McMaster-Carr
.That should make it pretty water tight. Now use 2 each cam straps around it so it can't pop open and you are ready to go. Both can be sat on but the 24 gallon is smaller so it can handle more sitting weight because its sides are closer to the center of weight. AND THAT'S THE POOP!!
Anyone else have any IDEAS please post em.