I think you can easily add a palmas palmas, delhezi, Senegalus, and the black ghost knife. It should work out fine majority of the time.
Cichlids can pick on bichirs so they need to watched.
The only thing I wonders is.....what are ur other bottoms feeders you mentioned.
If it less than the girth of the bichirs then it will try to eat it. So u want fish that are more than the girth of the bichirs. Also the same for bichirs as they can be cannibalistic. Especially if u feed with feeders but less likely with the mentioned bichirs compared to an endli. Also once the ghost knife gets fully grown then it can eat small tankmates (neons etc).