Personally, I think that is too small. They may only be reptiles, but from a humane standpoint that is not enough room. I have my females in groups in 40 gallon tanks and they like to come out at night and check things out, climb around a bit. I mean, we could keep people in 10X10 rooms and they would live and breed, but the quality of life wouldnt be that great. The smaller the cage is the more likely that your animals are going to be stressed, which means that though they may be producing just fine now the long term consequences aren't so much fun (lowered immune function, shorted life span, ect).
I use ten gallon tanks for my babies, 5 of them per until they get to be 2" SVL. Then they are either split up or moved up to larger housing.
I also find that cresteds prefer screen enclosures as they offer better ventilation and they can cling to the mesh better than they can to the glass. This gives them more usable area for the same space on your shelf.
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2.10.20? Crested
1.1.3 Gold Dust Day
0.1.0 Presa Canario