I love this and hope you do well and the vets take advantage of this.
yes ATO ppl dont realize just how much water fish drink!

I really like the micro version of the auto aqua it's small and does the job perfect.
I am sure you have thought about this but..
maybe an optional upgrade to a 40B for some folks? I really think the 40B are the best little tank to start off with. i know i know lighting can be a pain ( but DIY is an option ) but other than that I think there great. I feel with a 20H they will want/need to upgrade anyway where a 40b can be around for years.
just a thought!
you can host workshops to build stands/ DIY rock and make it a fun therapy playshop where vets can come and hang out.