Welcome aboard. You're going to encounter a problem using a hex tank for a treefrog. No one makes a screen top for a hex aquarium of any size and treefrogs require good ventilation. You will have to make your own. Good luck with that.

Since you're in Plymouth you should come by the New England Wildlife Center in South Weymouth for the New England Herpetological Society's next meeting on the 14th. For more details see - http://www.neherp.com.

Also the NEWC does have second-hand caging and other equipment for sale. You may find something that may be easier to work with, for a very good price.

Hopefully, I will see you there.