I have fished Bel Haven many times with my kayak, launching from the park south of the Marina, and also from the kayak ramp at the marina ($5 fee for launch and parking).
It can be excellent for bass, especially late in the evening on a high tide.
I would not think it would be that great for a tube - pretty long distance to what I've found to be good water, though there are some sunken trees not far from the marina launch and you could fish under the moored boats.
I got rid of my float tube several years ago, but I would think Riverbend park would be good, you could go upstream and float down while fishing all the rocks there wehn the river was low and slow, and the water warm.