Don't forget that the San Filipe 250 course essentially ran D1SS1 and D1SS2. =)
If the course is essentially the same every year, I don't think it matters if they allow pre-running. If the course is going to be substantially different, I would suggest they just keep it secret until race day.
The organizer taking a special few on a pre-running trip with a new course isn't super cool though...
Thanks to Scuderia West
for their support in the 2013 Mexican 1000