You could add maybe 6-8 panda cories, more platies, mollies, and I would add two female gourami if your existing one is male.
I'm not sure how big the loaches get, so I'm just guessing four inches.
5 platies (~10 inches)
5 mollies (~15 inches)
3 dwarf gourami (~6 inches)
6 panda cories (~12 inches)
3 kuhli loaches (~12 inches)
This gives you about fifty-five inches, which is fully stocked by the inch per gallon rule. Depending on your filtration system, this may be perfectly stocked. I'm not sure about the size requirements of this loach species, but I know that clown loaches can be huge, so keep that in mind. This stocking would also keep each tank level occupied. Of course, it allows no room for new species besides the pandas, so if you want a different species, you'll have to lose some of the live bearers. I would definitely recommend the two extra gourami though. I've been reading up on them and the general consensus is that these peaceful gourami like to be in small groups.