We had a thread about this a few months ago here
Perhaps you can find some inspiration there as well.
Thanks for the link, it was an interesting resource. However, I don't think we'll have both pits open, try and make it a bit more of an endurance race.
Our league in Dallas - De Trippers in Dallas - which usually runs 3 lap races - does the following modifications for "The Big One" - a) 2 laps instead of 3. b) 24 wear points instead of 20 & c) 4 wrenches instead of 2.
I think that is a solid suggestion. I'll get a vote from the other racers and see what they think - I'm sure none of them would mind a little extra help!