I would have to ask some questions first to get a better idea of your thinking. Why do you like the bare bottom? If it is for ease of cleaning, using dirt is not the way I would go as dirt is what you are wanting to remove!
Sword are big folks who do lo9ts of roots and a potis going to get full pretty quick so I might recommend going with something much wider rather than deep so that the roots can spread. I often have swords in 1 1/2 -2 inch deep sub of mixed variety things like pool filter sand, gravel, dirt, and whatever happens to get mixed in the rest. They grow okay in most anything but do get large! And mixing brings yet more questions as to what fish you will have as many will move the sub and that means it gets out of the pot quicker.
Maybe a combo of some bare tank, while the plant lives in a shallow tray that is hidden under things like rocks. Whether flat slabs or rounded, the rocks can ease the question of digging or sub scattered around the tank if that is a real concern to stick with.
I'm a river/ creek guy and like the look of plants growing up out of wood as it does so often in nature.
For a semi-mobile plant, wood or rock, combo, how about a flat slate floor tile with shallow tray of sub and plant screwed on and the decor item to hide the tray all attached as one unit to be moved if you are wanting to clean under it better. Something like a flower pot on the deck except underwater?