I have the same problem floating the Sabine River.
I haven't tried this yet, but I just saw it and it looks like it would work great on a float trip. I think I'll build a set to use on my yak because it breaks down so short. You would need a good anchor but a piece of rebar or even a stick driven into the sand should work. It would even be easy to add a third leg that folds back towards the hammock and that should make it bombproof. Might be worth a look for you.