I've seen something like this on lakebeds when the water goes down, just not much habitat on them.
If you use a cinder block cut 1, 1 1/4 or 1 1/2" PVC to 10 to 12 inches long. Put a screw in it about 1 inch from one end. Set as many pipes as you wish in the block and fill the block with concrete not the pipes with screws at bottom. After the concrete cures put a screw in about an inch from the top. Stack the blocks and bundle of habitat in the boat and head to where you want to drop them. Remove the top screw and stick a piece of habitat in the pipe and replace the screw. After all the pipes are filled it's ready to drop.
The PVC will need to be a bit longer if used in a bucket. A screw can go through the lower end of the bucket and into the PVC for the pipes along the rim. A screw at the top of the bucket and through the PVC to hold it in place and serve as the habitat setscrew. PVC pipes in the center will have to be taller with a screw close to their bottoms. Fill the bucket with concrete, not the pipes. After concrete cures put screws in the center pipes. Set the buckets in the boat along with bundle of habitat. Remove the top screw and stick a piece of habitat in the pipe and replace the screw. After all the pipes are filled it's ready to drop.