On some of these climbs and or decents the shorter based vehicles will be at a distinctive disadvantage, Whatever events are done need to be evenly based for all who may show up driving whatever. Or have classes for vehicle/tire size, ect. Just something to thing of. Hate to see someone get hurt or damage their vehicle trying to participate. I guess what I'm saying is something for everyone. 
We can't do much about wheel base except making any turning obsticales even for both. On the trail SWB and LWB each have their own advantages and dissadvantages. I simply brought up wheel base because if we made a obsticale course with tight turns then i could kickass in the jeep making turns where as lwb vehicles would have to do several point turns.
We could do a stock- 33" Class and a 35"- unlimited class.
But keep in mind the more classes we make the more time its going to take. And in hine site it will divide up the group as a whole. So I will leave it to a vote. But I think there are way to many variations and ultimatley someone will whine about it not being fair .
For Example the trail Bronco Buster. We had a large number of different class vehicles on that trail. and I think they each had there own advantages and disadvantages. But they all made it with no problems.
Bronco buster is a level 4 trail-
Ernies ford- BB 390- 4spd- Locked Front and Rear 38" Boggers
Noahs PW- 300hp 318- 4spd- Locked Front and Rear 33" BFG
Wills RC- 360- 3 spd Auto- Locked Rear 36' Swamper SX
Erics Blue Jeep- Built 304- 4 spd- Locked Rear 33" Mud Kings
Daves Brown Jeep- 304- 4spd- Opened F/R - 35" BFG Kralwers
Ron's Creations- 318- 3 spd auto- Opened F/R- 32" All Terrians
We all Did that trail at pretty much the same pace with no issues. Now all are vehicles are very different in Power, Wheel Base, and Traction. But can anyone honestly say who would be fastest based on the stats of the truck? I don;t think so. I couldn;t even bet $100 on who would win.
Thats why im leary about classes. My jeep flew up some obstacles that ernies ford had trouble with. And Ernies ford also went through obstacles easly where i had problems with. And those are two completely different machines.
But here is another example- Dave's and My Jeep. Both CJ7 4x4 304 4spd Jeeps. His is has 6-8 inchs of lift and 35" BFG krawlers. Mine has 4" of lift and 33" Mud Kings. If we did Classes Him and I would be in two separate classes even though are Jeeps are al most the same. Now My jeep has a rear locker and his doesn;t. That right there made a differents of night and day between us. Dave would have to throttle up a ton more and bounce all over the place to get up obstacles where i was able to gear down and walk up them. But he also didn;t bottom out like i did on some obstacles. Just food for thought.
I think if we do all the events some will do well in some events and others will do well in the other events. I think it will equal out.
I would also like to do a barrel run, location is the difficult part.... water on the course as Ron suggested would be a fantastic idea to keep dust down and slick it up a bit!
Have we considered a Krawler Barrell Run? Same concept except in a area where there are obstacles we can set the cones/barrells on.