It's fairly simple to make a divider if you go back to that idea. Make rectangular panels in an appropriate size and cover them with hardware cloth wire. You'll probably need two or three panels so you can fit them through the door when you're carrying them in or out, and you may need a triangular panel for the roof section. Make one of the panels an appropriate size to serve as the door between one side of the aviary and the other. Attach the wall panels to the sides of the aviary and to each other with metal brackets. Attach the door panel with hinges and install a latch. You probably won't be able to attach them to the floor since you have a tile floor, so just make sure there's a fairly snug fit where the bottom of the panels rests on the floor.
It would be sort of like this, if you imagine that the outer wall facing the camera is inside the aviary and the smaller panel on the left is actually a door.