I can't comment on the bunkhouse situation as I was camping on week one.
However, I would HIGHLY recommend an ATV if you've got one. Unless the ranch has dried out considerably (I doubt it) a two-wheel drive truck would be less than useless.
I was driving 'The Beast' that Don, Curt, JC & the boys used for a day & even with very aggressive mud terrain tires & a 4-wheel drive, low ratio box we struggled to get to some places. At the river crossing we used on the last day, it took me 4 attempts & 25 minutes to get up the far bank which isn't actually that steep! A guy with no offroad experience could easily get into a lot of trouble on some of the roads. I don't mean to sound alarmist but 12-17 miles is a LONG way to walk for help! Cell service is spott at best & you really don't want to get yourself into anythig you ca't get out of by yourself. I would certainly recommend throwing a long handled shovel in your kit for those wonderful digging-out jobs
75% of the roads are fine for a 4 wheel drive truck with good tires, but the other 25% have steep dropoffs, 2' deep ruts & the mud is like axle grease, both sticky & slick at the same time. If you value your paintjob at all, hitch a lift! :D
Mind you, if you enjoy a bit of offroading fun (I really, really do!) & don't mind getting dirty, driving around the ranchis half the fun of the hunt! :D