that sounds interesting! My main interest is finding a 5-band antenna that is at max 12 - 10 m so that it can be used as a vertical on a 10m mast.
If your design does not use a loading coil, then you should have a look at the 3-band EFHW by Heinz, HB9BCB:
His design is IMO the state-of-the-art in SOTA antennas, and pretty popular afaik.
17 and 15 m could be added by links to the first radiator segment; this is actually what I have on my list of projects.
Even a bit more elegant would be to make the end of the antenna at the rig / transformer side detachable so that you can shorten the 20m radiator part from the rig side. I took this idea from Brad, WA6MM. The 20m trap should also end the radiator for 17 and 15m, and you would not have to lower the mast to change to these two lower bands.
Attached, please find a few pictures of my proposal. Maybe Heinz and Brad can take a look with their expert eyes.
73 de Martin, DK3IT