I guess adding anything else is going to cramp the conditions further. A friend of mine has kept too different size Pygo's in a small tank for a long time. That tank is next to bare, just a few plastic plants. Thats not to say it will work for you. Everything is fish dependant, ecery fish is different. I guess it will be a case of keep your fingers crossed.
You do have the option of completely cramping the conditions and dividing them. This would certainly be a little cruel in a small tank but they are more likely to be fine. And it is only temp