Thanks, William! This is exactly the direction we need. At some point I watched both those videos, but at the time they were just head-scratchers to me. I tried to look up more about the Hornito design but was coming up empty handed. I just did some more serious sleuthing and found the design is apparently the property of PODERCO S.A and developed by Robert Lerner. Since more searching found me this pdf of a stove design by the same person, although it looks different from the image you posted and I can't say I fully understand it or that it would help me build anything:
Maybe more experienced RMH folks can help with an actually buildable design. I don't have very much hands-on rocket stove experience at this point. I may be able to employ some folks to design and build one of these, though, so if anyone is excited by the prospect of doing that, contact me.
I like the idea of saving the oil, it seems potentially less complicated than having to count on it to finish the current batch, easier to just stoke with already prepared fuel.