I like the idea of reptiles basics rack for colubrids but the size maybe an issue, if you wholesale your corn right away or move them very fast it won't but if you are selling them retail and it takes a while 6 quarts maybe the best option.

I use to house my Milksnakes in 6 quarts tubs from AP (Economy line), looks huge at first but it gives them room to grow and you can use that rack for other species as well.