Andre-
10,000 speakers, or whichever other number, does not sound like the best of limits. For one thing, I don't want to disqualify the Nauruan Wikipedia (or the Manx one, for that matter).
I personally don't think Nauruan and Manx will ever get anywhere, and speakers of both are almost always bilingual in English (the ones who aren't are unlikely to have access to Wikipedia). Nauru today is primarily an Australian prison colony for "dirty immigrants".
However, in the interest of wikipeace I would be willing to accept your 50 document requirement, provided that we are talking about *non-digital* archives (the word archive is far too vague otherwise). The burden of proof should be on the person who wants to start a new Wikipedia.
Furthermore, I suggest that the Toki Pona Wikipedia is removed from Wikimedia and moved to the Unilang wiki instead: http://www.unilang2.org/main/wiki/wiki.phtml
It seems to be perfectly suitable for that purpose.
Regards,
Erik