i wouldn't take my coach on it only because of washboards and dust other than that it is not to bad. have seen tour bus , class c and one 5th wheel on it.
you can reach natural bridge on nice paved road from blanding if you don't feel to adventurist (spell check's not working)
We watched an approx. 40' class A do it last summer, so a 26' + 21' should be fine. And if you watch the YouTube Video in the link above, it's an 18-wheeler. Around the 6-minute mark you can see his trailer in the mirror. And the comments on YouTube say he also tows his 57' spread axle drop deck trailer up and down the dugway as well.
You should be fine. It really just depends on your comfort level with grades, switchbacks, and no guardrail.
Afterthought - while I'd be comfortable doing it in either of my rigs (38' DP & toad, or my 38' 5-er), the DW would never go along for that ride. She ran up and down it with me in our Jeep, and even then she made me drive as far away from the edge as possible.
My point: It's definitely doable, but you really need to consider the comfort-level of your passengers, in addition to your own comfort and skills.
Best of luck to you. If you do it, take pictures and post them later.
Thanks! Good Information. I have seen the video - that is what made us think it was possible despite the signs at the bottom.
We travel a lot of back roads; gravel and washboards are the norm so won't be a problem. I have an issue with edges but, having already done the road and survived, I don't think I'll panic enough to not do it. From experience, roads like this are harder on the passenger; when one is in control of the vehicle, confidence is much higher.
I'll definitely post pics!
2008 Ford F250 diesel
2013 Keystone Sprinter 277RLS