If you look for plants on driftwood & rocks you get the best of both worlds plants attached to
Hides that are easy to move ' clean around as well as being much hardier low light loving plants.
I'm not sure about the soil you linked to except to say that covering it in sand doesn't mean your lotl won't go rummaging through the sand to get to it... If your covering sand adds too much depth you'll risk have gas bubble build ups which you need to stir up the sand to get rid of them, if there's layers it's going to be even more difficult to keep it neat.
<3 >o_o< <3