Well, I'll have a prototype done tomorrow afternoon, and I'm thinking it's along your lines of thinking.Would be awesome to build a grate over a bit of a tub, but weld the box so it drains all of the run off to a bucket. Damn wish I had a welder haha!! I could probably fix something up with wood. I’m pretty handy with it
Here is a general idea...
I took a piece of 1x1 square tubing and left a nice slot. The twelve 5 gallon buckets will drain into a channel from both directions into a T, draining into the reservoir through the slot. Least that's the plan!