If you really want to know
everything about camping at the Fort on Thanksgiving, read these three reports:
TCDs Thanksgiving 2006 Trip Report
TCD's Thanksgiving 2008 Trip Report
For any TCD fans out there, the 2006 trip report is quite remarkable. It contains exactly 10 posts. My, how times have changed
TCD
Oh, and the short answer to your question is that Thanksgiving is the
best time to camp at the Fort.
Period.