Paul, you may already know this since you linked to the wilderness.net map but I believe that you can find fairly reliable acreage totals for the Pasayten here:
think I saw at least 2 TR's from that area (Cathedral Peak region) on cc.com this season! In fashion eh? (maby 'cause N. Cascades seemed wetter this season).
wish we could - out of vacation time & can't pull it in a weekend (even from Canada I think it's too long)...hopefully next year. Amazing area - looks like the Wind Rivers a bit I think.