well, those flat containers are cheap, make a couple a few different ways and see what works best.
I have piles of "didn't work so well" pieces.
here is a thing kinda like yours I made years ago, it actually worked very well. I got a big 2 gal
watering can with a spout that was long enough to be usable, packed the inside with plastic pot scrubbers (I love those things) and then pumped water from the tank into the can, and placed the spout where it would flow back into the tank.
It took up to much room but it was fun to watch work.