This is a good idea with this 120 gallon back up plan.
This happens a lot with model railroading in that I have tried to build a 40 story HO scale skyscraper at home but I ran into the proberm of trying to find enough of the type of HO scale kit that I was going to kit bash to make the 40 story skycraper so I ended up with a seven story tall building that at a later date when more suppies come about I could always start enlarging it into a larger and taller building with more stories.