yeah pleco would probably be ok though if i were you i would try and find a pleco that doesnt get as big as a common (like one that stays about a foot) there are some really nice colorful plecos out there that should be able to work with that tank, normally cichlids leave plecs alone for the most part (unless you get fish like mine, cant figure out who it is but one of my fish literally skinned one my rubber lips and the other one has to stay in hiding

hopefully this changes once he gets a little bigger) as for the JD though i would just wait it out and just watch them to make sure nobody is getting seriously bullied and dont really worry about it until a problem arises and make your decision then (thats what im doing with my tank, they are all juvies and im just going to remove the troublemakers as they arise)