For a second I thought you meant the prayer plant was 20 inches tall.

Seems like prayer plant might be a good one to plant right next to the water to act as a canopy over the water and maybe even give the frogs a natural way to get out.

I will likely get a pothos or two, nothing like another fast grower. I don't mind trimming and once I set up the new tank I will be able to make it possible to lift parts of the top to limit the escapement possibilities.

I am surprised all of those plants are happy in the same little cramped amount of substrate. But they all like to be a little root congested so why not.

Last thing should be to find a ground cover, I love mosses but I have never had good luck with them.