please call me Anthony, my friend.
As best I can visualize, your notion sounds essentially fine. The vessel is small enough that manipulations to get the pattern you need will be relatively simple. No worries.
I do have some wonder and minor concern about the egg grate barrier. I'm not sure its needed and do expect that it will trap or hitch some Chaetomorpha.
Actually... in the big picture, you may not need to tumble Chaetomorpha at all in this refugium. Again, it is small enough in size that lighting and water flow will not be as difficult or expensive to produce as on a much larger refugium.
And since I'm a (very) big fan of keeping systems as simple as possible, I'm suggesting you maybe forego most of the customizing of this vessel and see how it flies at first. Adjust as/if needed afterwards
best of luck, life
Anthony