Glad you're enjoying the mod! As far as themed megawads go, while it'd be fun to make another one or two space britain maps I don't think I'd be up for a whole megawad- both because of the time/work investment and the danger of ending up adding too much extra "lore".
I kinda like the idea of Stone being like a GI Joe figure with just enough lore on the back of the box to be going on with, and a deluxe pack of accessories to tear up whichever playset you put her in lmao