As far as skidding the logs... I just read 11 pages of OVERTHINKING. You know how a logger would do it? You put a choker around one end and drag the bitches. That is why it's called 'skidding'.
Block and tackle, PB's, chokers, and chain and cable are some of the basic tools of the trade that will be needed.
There is alot of good things here.
My thought is Basicaly a rear stinger( not to tall ) with a block atttached to the high point and a rear winch. The block needs to be able to swivel and allow for us to atach to a log and drag it to the buggy. WHen the log gets close enough the block placement will lift the end slightly and you drive and place the log.
Bash plate needed with maybe some bolts or somthing welded that may help the log stay on the plate.
If posible you only want to have to set the choker line once, any more and its a waste of time.
Food for thought. Think very very tight trail with ruts you cant drive out of.
If we where doing this with straps and a winch we would snatch block the tree onto the trail. When the butt of the log was on the trail we would then remove the snatch block and either drag or winch the tree into place.
So with that if the back end of Marks buggy is able to do the work of the snatch block and then also the drive/drag/winch the log down the trail there is less rigging invloved.
I really hope that makes sense. It only requires a mount for a block and a rear winch.
Other things to think about if you have a winch that will hold 100 ft of cable only run 50 ft, then you dont have to watch it spool up. and if a block is acting as a second fairlead the winch can almost be unsupervised. Which can then be a 2 man team instead of a large group.
I dont think the rear winch(1700 lbs) and your air shock method is a good idea. I think it would sorta work but for how long? THe extra pressure in the shock will help over all. and it also relies on flat ground. If the log is in a hole your shocks may not lift it up high enough.
A good ring on your rear steer armor may also be a good attachement point/tow point.
I really hope that all makes sense. K.I.S.S. is usally the best.