"Been there done that" on the kiddy pool. I tried it only one year and I put it too shallow I believe. I had a couple of larger rocks in it with the gravel and the fat heads loved it. I still think it will work.
Last year I put together some pvc pipe in a rectangle and covered it with a poly tarp. I drilled holes in the pvc to let the air out and sunk the unit and then poured gravel on it. Fish were on it the next day! I made several more like that and had lots of fish spawn on them.
My ponds are weedy and weeds tend to creep in from the sides. I think my best option would be to do as Jim suggested and build a platform in deeper water. That will be a bigger project.
