I bit the bullet and bought what I hope is a pair last night. I think I got the only female in the tank. I drip acclimated them for about an hour. They turned really dark. I didn't know they could change color so markedly.
I was on pins and needles when I added the rams to the tank. So far, so good. The betta has left them alone and they're eating flakes pretty well. I thought the betta might be antagonizing one of the rams, but he was just chasing food.
This morning I had to watch the tank for about fifteen minutes after I fed the fish before I could find both rams. The female found a nice spot in the corner. I found her after a minute or two. The male finally came drifting up from under the water sprite. Both fish were fairly pale, but I think it was because the lights had just come on. Maybe I'll try to get some pictures this evening.