Not much ram specific advice for you in afraid, wanted to follow the thread though since rams are on my " want!" List.
found the info and pics from Cass and Rebe so useful too!
Re floating plants -success with particular ones varies on so many factors and tanks. Nutrient and mineral content, the light you have, surface disturbance... One type not thriving for you doesn't mean they all will! I've had Amazon frogbit & water lettuce thrive for years (and duckweed of course, despite all my attempts to murder it), haven't tried Salvinia yet.
But I desperately wanted RRF. Tried at least five times. Grown in- vitro, melted away to nothing in days, no matter what tank. Some from fellow hobbyist, since larger and more of them, lasted longer, but still just dwindled down til I had none left, in each tank.
Have given up my RRF dream for now. But will still try again someday! In the meantime though, frogbit & water lettuce still working well for me! And no worries growing plants in sand either. Root tabs added, especially greedy root feeders like swords, crypts, and vallis also does much better with them. Just stick with name brand ones. Even Tetra root tabs have done well for me, but seachem and API good too.
Just don't make the mistake I & another member made of buying cheaper, no name tabs that could have anything in them, and cause an ammonia or nitrite spike. But I know you're a researcher & would get quality.
I would add a good amount of leaf litter & maybe botanicals especially because of lighter sand, but you know what you're doing! Happy you got him, and that he's less stressed and settling in now!