I have a almost new pair of paddle pushers for sale. I think they are no longer made. I’m not sure I’ve ever used them, and am selling my float tube because it isn’t being used, either. (Pontoons are AWESOME!) Here’s a link if you need clarification.
They allow you to “walk” in the water, and will move your tube forward instead of backward like your kick fins, but are not as fast as fins. I don’t recall exactly the size I have, but they fit my size 9s, although I don’t think they’d go much bigger without some modification.
$15 shipped.