Don't suppose you're likely to do something similar for WW1?
I'd be willing to consider it. I think only the German symbols would have to change, actually.
RN still uses the White Ensign.
US was still flying the 48-star flag.
Italy still using the same flag.
Japan, ditto.
New German Imperial naval flag in black/white/red.
Add Imperial Russians?
Add French? (would also cover WW2)
That's not a huge amount of work. I'll see what I can whip up.