I have two of these...
Not my photo -
I have no running water at my coops and about twice a year I will run several 100' garden hoses out to the coops to fill these. I use the water for the birds, cleaning equipment, washing hands, etc.
We bought them from a friend's dad who had a flood and they floated away into a wooded area. He didn't want to go get them so he sold them to us for $50 but we had to drag them out of the woods. I love them and always keep my eyes out for more.
We built a rack for each that raises them off the ground about 2'. Its enough to get a bucket under the valve and makes it possible to stand while filling stuff. We also had to replace the valves and I connected a short hose with a shut off on the end.
If you had one of these, you could keep a pan(s) under it and just fill it daily. I have considered leaving the valve open enough for a slow drip into a pan, but have never tried that.
I have some issues with those tanks- the place where i work cuts them up and disposes of them, môstly to keep from being sued. They are listed all over Craigslist from $50 to $80. Cleaned ones around $100. Cleaned from what? If they are not food grade, i'll pass. Clorox and baking soda just not what i think has sterlizing from acids adhesives and other chemicałs. I might be wrong but i am safe. My dogs and livestock are safe. This doesn't mean a creek is safer. Those tanks are purpose built for shipping and storing the above. Many of them from the Auto industry.
Your method of standing them up helps with gravity feed. I'd really whould like to tie our house gutter system to one or two. I just don't trust the residues in them.
We bought 2 of them to make an aquaponic system. They were $40 each.
There's a water treatment place in Alabaster that sells them. They get them from Alabama Power, they have the oil in them used for the turbines in the dams.. obviously safe enough to end up in the lakes. Nothing Dawn doesn't take care of. We used an angle grinder and cut ours open, because that's what we need for our project... so we'll be able to really get in there to clean them.