I've gone that route twice in two different 38ft motorhomes towing a car. First time because I didn't know better, the second time many years later because I forgot! It is beautiful, but scary and dangerous. Going north you are on the mountain side, rubbing up very close to the cliffs, and quite a few really tight turns. It makes it hard to drive and enjoy the scenery. With a 38ft rig and trailer the turnouts are not really an option. Few are large enough to enter safely and be clear of the road, and if there are cars in the turnout it becomes out of the question. Going South on the ONE puts you on the drop off cliff side, often without any significant guardrail. Sure, maybe a wooden rise, but nothing that would stop your travel down a 100 feet or so. The real danger comes from those trying to pass or those coming at you and over-riding the center line. Do realize that plenty of delivery trucks, box trucks and larger routinely travel highway one in the course of every day business. If you are really experienced with a box truck, and you will only be 26ft or even 28ft the drive would not be much different than taking a large van. It all depends on your true ability. It is a beautiful scenic road, and should be on the must see list.