How about saying "there can only be X policies on the Wikipedia, where X = the number we currently have. If you want to
add another
one, you must first remove an existing policy, by consensus." I.e. keep them constrained within a busy loop, fighting
each other's
policies. For bonus points, as time progresses, you could try gradually reducing X (using a Last-In-First-Out approach), thus forcing people to condense the rules into "meta-policies" (such as "assume good faith"), rather than obsessing about
petty details.
And when the rules fit on the back of a Wikipedia membership card in 14-point font, then it's time to stop reducing X. :-)
That's a good policy! Now, let me go make a 200-square-foot membership card.
For the purposes of this exercise, I was assuming something the exact same size and shape as a credit card, with a Wikipedia logo, your real name, your username, and possibly date you started using the Wikipedia, and maybe a photo, on one side; and the rules on the other. If you wanted the card to have a functional purpose (beside just as a symbol of membership), I guess you could have a smart-chip embedded in the card, which could optionally be used somehow as part of the login process, when inserted into a card reader.
However, I was not thinking something like the International Driver's Permits, that's a bit of paper that folds out a number of times to become the height and width of a newspaper, with tiny legalese writing all over it! :-)
All the best, Nick.