[OS X Emacs] Aquamacs: how to start with "minimal" customizations?

[Marius Hofert]

Hi,

from time to time, I would like to test out some settings I would normally put in Preferences.el. But in order to make sure they do not interfer with the preferences I've already set, I would like to use "Aquamacs without customizations but one-or-two minimal settings". I know I can use Help -> Diagnose and Report Bug ->  Start Aquamacs without customizations to open a "fresh" Aquamacs, but how can I open a fresh one with some minimal preferences (for example, just containing (setq-default fill-column 80) to try out what this does and how it behaves)? So far I typically copy my Preferences.el to somewhere else, then remove everything in Preferences.el but the new settings I would like to check out, then save + restart Aquamacs. Needless to say, the settings I haven't set via Preferences.el may still interfer, so it's not a real "fresh" Aquamacs setting. What's the best way to do this?
Total newbie question, but hopefully time-saving for the many newbies... 

Cheers,

Marius