Looks like the lighthouse could be removed with some judicious hacksawing, filing, sanding and touch-up paint and then you'd be back in darkness again.

Speaking of weird mods, I knew a guy who drilled a hole down through the top tube of a Serotta Titanium SuperTourer right in front of the seat tube so he could glue in a brass wood screw to act as a pump peg. That's not the weirdest bike thing he did.