I did the enduro out at Infinion last year for the nor cal region. Its Tag only. they do a avg. weight of I think 350lbs for kart and all drivers and use Yokohama Y01’s which held up pretty well. I found their rules on line which might help put things together. It was an awsome time.
http://www.jimrussellusa.com/karting/2005_Enduro_Rules-Rev_Sept1.pdf
Im in if its on the denver side of the mountains going out to GJMS just adds that much more money and TIME. The track @ Centennial????????