I would work on the little one right now, do a ton of research and get all of the automated stuff working on it now, then perfect it, then integrate it into the new tank. I would love to see how you plan to automate everything. Perhaps you could get it rigged up so the waterchange could work with the push of a button and just have someone at home push the button every week.
I don't have the slightest clue, at the moment, how you would work this, but isn't how most of this stuff starts?
PM if uve got some ideas or wanna talk about it