maybe just a flat piece of metal.. one of those that has the holes in it that you can drive into the ground? You could then attach it to that. Or a plastic bucket.. fill it with rocks.. drill the hole in the side sink it in the water.. that would be stationary.... just about anything that can go down in the water that you can put a hole into and then attach the washer and float to.
Raised Ponds easy, cheap, fun and portable
That may do the trick...need to talk to dh and see what we can come up with.