You must have done something by now, but I can recommend a great little book for tub gardens by Ted Coletti, who will be speaking in a week or so at the Aquatic Gardeners Association Convention in NC.
He gives tips on growing many plants in his tub gardens. His idea for waterlilies for little containers is to limit their root growth by hardly any growing media. It cuts down on the blooms, but at least you can get some if you are limited in space.
[url=ttps://www.goodreads.com/book/show/57757108-the-tub-pond-handbook-3rd-edition]ttps://www.goodreads.com/book/...[/url]