I've seen some good "coffin" blinds made out of plywood,fiberglassed to make them watertight so you can set up in shallow water.I made a cart/blind out of 1 inch EMT conduit,added wheels and blind material.Came out decent and only cost about 40 bucks in parts(I got the conduit from a dumpster)
You probable should post this on the hunting gear forum,might get more replies.