I meant anacharis and cabomba will quickly grow. Often longer than water depth thus begin to grow sideways on the water surface. Those that grow above water will die.
Water wisteria, ludwigia, bacopa, (don't know what else) will grow and survive above water if stems are strong enough to support it.
You can use anacharis and cabomba at the back. . . Lets say 2-3 layers. This should be sufficient as getaways. Combine them with swords and bacopa for esthetics. Anubias can be placed somewhere in the middle as they will be attached to wood. And scatter your marimo at the front.
This is one of my latest "test" tanks (about 7g). I want to make a real planted but algae always over run them (70-80% and even 100% planted rule doesn't seem to work for me nor does reducing light). With the help of nerite snails this tank seems clean (about 2 months now).
Back - very long grass like plant, anacharis, a type of cabomba, ludwigia, and a sword.
Mid - bucephalandra tied to wood, a type of fern tied to wood, anubias tied to rocks and on substrate, crypte
Front - initially I wanted to use monte carlo carpet. But I read ppl saying lack of light will avoid carpeting. So I covered it with more tiny bucephalandra (I'll take a picture tomorrow). . . . . This is heavily planted - only meant as an example. You can reduce plants in yours.
Btw, currently there are 4 nerite snails, 3 juvie bettas, 4 corydoras.