Discus need at least a 75 , 120-125 is better , don't they recommend groups 5 or more , going 55 skip any tank mates , super warm water there is only few options , peace
Rams come in many colors choose your fav b go for it. Rummynose tetras for dithers. Bn plecos for clean up they have variety of colors now too. I have 3 sterbai 2 ABN plecos 15 rummynoses and 9 discus. Wouldn’t want anything other than the discus showing the tank they are beautiful enough.
I'd skip the bn; while not common they can latch on to angels and discus to suck the slime; and yes i had a bn do that to my angels - made a nice mess of them until i got rid of him; though after 3 or 4 months they did heal up.