Def. need a back stop. It helps prevent accidental escapes. Also I would unspace the tubs. Any little bit of room for the rats to get their teeth up and over the edge of the tubs will result in chew outs. Also Def. go with the autowater system we conect ours to a 5 gallon bucket and it is gravity fed. We have been building and using similar if not exactly the same rat racks except we add wheels to ours to move them around easier. That way if one does get out moving the racks is no big deal.