I think that the naval war might make a good expansion for WOFF.

Brandenburg seaplanes raiding British towns. RNAS raids on Zeebrugge

Reconnaissance missions looking at shipping in the channel ports or U-boat raiders.

Of course, the RNAS mainly used airships for anti submarine patrol.

There was a Felixtowe flying boat in previous versions of the game.

I have had ideas for a mod in this direction (channel ports with shipping) but my modding skills are still in their infancy so this is some way off yet.