The additional toe was the Porsche techs suggestion since he's done a number of club member cars. BTW, that's .16' on each rear side for a total toe of .32'.
I can't say I've seen or heard of another rear setup with this much toe--any ideas of how what the max toe-in would be?

You're right--it sounds like too much tire pressure in the rear; given the low temps I wasn't expecting the tires to get much over 40 psi.