Great tank! It's so thrilling to have this huge amount of water to populate.
For the plants, we did the same in our tank as what you are doing: just wait and see what grows well. Filtering, water current, substrate, population, water level, all these factors and more will influence which plants will like your monster tank or not.
In our 1400 Ltr for example, there is a lot of "dust" in the water due to 9 Botias playing fools, so plants like Limnophila, Cabomba
suffer from too much deposit stuck in the leaves, so I had to take them out.
I found that Rotala rotundifolia
is really beautiful in a big tank. Apparently you will have plenty of light to turn them pink. The difficulty with neon light in these monster tanks is to have light reach the bottom, so the bottom plants need to be very robust.
For the red touch, I find Ludwigia repens "rubin"
to be robust and not too demanding compared to Alternanthera
which never grew well in my tank.
Can you tell us a bit more about your filters? Everything is so well hidden in the setting that it's difficult to imagine what's behind and how it works.
Great project! And lots of pleasure ahead!