Jennifer, it is 6 hrs one way and not particularly rough. The nature of the rocks on the road and the gas patch truck traffic make flatting likely. River Runners does a great job, but what i do after 20 years of that shuttle is call Redtail Aviation in Price. Drop your gear at the put in and leave a rigger or two then drive out to Green River. Get a motel and drop your boat haulers at Swasey's then drive to the airport for the shuttle flight. Keep your fliers to 2-3 persons, small light and cute if possible. You will fly up the canyon and land on the bluff right above the put in, (a 30 min walk off). It is faster cheaper and more fun. And you know for sure all the vehicles made it without flat tire upcharges that are fair the other way, but can be a pain for the drivers. If you want all your vehicles @ the take out most hotels will get a driver to follow you out to Swasey and take you to the airport for $20 or so-30 min drive- semi paved. Plan the flight for early morn to avoid turbulence and tip the pilot, if he didn't go inverted. If he did then tip more.
I've done my shuttles this way for 30 years and never regret it on Deso, Cat, ect.
Feel free to contact me for #s and other info. TFoot