First off, both of those tanks are overstocked. And I second the fact that keeping one neon is not a nice practice and the fish would greatly appreciate friends, though there is no room left for any...
Anyway,
I don't think you even have room for a dwarf gourami, and I'd be weary about putting one in with guppies and all of the other surface fish in your tank. Guppies and gouramis don't get along well in my experiences. They are constantly in each other's way and get nippy towards each other. But, as I said, thats just me. I'm sure other people have no problem.