@dec_hl: Which is actually in heavy use at https://bromptonauten.cc/ (previously http://www.bromptonauten.de/)
And the suffix -naut is also used for other travelling persons: astronaut, cosmonaut, argonaut, etc.: https://en.wiktionary.org/wiki/-naut
And "bromptoneering" sounds more like modding and improving a #Brompton. (Think "engineering".)
"After a long day of #bromptoneering, the #bromptonaut brompted to his holiday cottage." 😎 (Why am I now reminded of smurf language? 😇)