I've just discovered that the 2009 issue of Studia Philosophica (published by La Société Suisse de Philosophie) was devoted to the subject "forms of irrationality". There is one paper which directly deals with skepticism, namely, Yves Bossart's "Sind pyrrhonische Skeptiker irrational? Radikale Skepsis und die Grenzen der Rationalität". (Unfortunately, my German is very poor, but I'll spend some time trying to figure out what the author says because I wrote a paper on this specific subject.) The whole issue can be accessed for free here.