I would say that a 72 is fine for Senegals and if you can get a 20g simp than that should help with the bioload. Thorichthys could work but they prefer to be in groups and that would be too many for a 72 as well as the polys. You could probably do a pair though. If your looking for a wet pet personality then a cool option could be a red wolf fish. Would match the theme of your tank and can be glass bangers. It’s hit or miss wether they allow tank mates but I think bichirs could be fine.