I have a large outdoor L-shaped pin. It is approximately 15' x 10'.it was for my Russian tortoise. But then I was given a female box turtle so for the short term I blocked off one part of it for her. my Russian, a female, would spend a lot of time pacing and Climbing and trying to climb along that one wall that I blocked. I think she knew there was another tortoise type critter over there and wanted to get to it. I could be completely wrong and I definitely hope so many corrects me if I am, but I have a feeling your tortoises would know the others are on the other side of the wall and may try to get to them by climbing or digging etc. she may have just done this because she was wondering why her doorway was blocked. There was an opening about 2 feet wide for her to go through only prior to me blocking it. This was two females, I wonder if it would be even worse with a male. Just a thought, your idea could work very well. Maybe some more experienced Russian breeders will tell me if I'm right or wrong on this.In spring I plan to build a larger outdoor russian pen. Until recently I had just one male. I now have 2 females also. I plan on dividing the one large pen into 3 smaller ones with some kind of easily removable walls..or a gate or some such thing. This way I can let them mingle while supervised and easily separate them. This way, I can try to breed them or not but its still one main enclosure. Looks good on paper anyway