We did Independence Pass going from Aspen and heading East in 2012 with a Toyota Tundra double cab 5.7L pulling a 23 foot Safari. Nice large parking area on top. Once you are on top... and heading EAST you are doing just FINE.
As you drive through Aspen you will see many restaurants. We stopped, had lunch in town and proceeded towards Independence Pass with trailer in tow. As you begin to leave town, as it seems to end where the entrance to Independence Pass begins... there is a very large sign. You cannot miss it warning that NO trailers are allowed.
Just great... as there is also NO WAY to exit. You are going to make it to Independence Pass and over... if it KILLS YOU. And, it sure can. You are on the guard rail side of the road, which is paved and well maintained. The drop is... well it is there and it goes down as you go UP. The road is wide enough for East and West traffic at the beginning, but obviously those blasting into the hard rock to create this road quit to let two narrow Ford Model A's to pass without incident.
It gets not only narrow about mid way, but if another wide vehicle is coming down... you cannot back up because of traffic behind you, and they cannot back up as the traffic is coming down. The only cure would be to pull your vehicle and trailer as close to the OUTSIDE EDGE so traffic heading WEST can pass. Then someone would have to proceed ahead when it widens... and widen is maybe gaining an extra three feet to "share". But if you get backed up here... it is a time to use some serious traffic control to remove yourself from this jam.
Lucky for me... we had breakfast early and once we were STUCK on this narrow highway for the first, and I will say last time... we made it up to the top without incident. The narrow curves are enough, barely, for two pickup trucks pass without locking... mirrors. Pulling a wide trailer... and not comfortable with a narrow mountain road, a dramatic drop that would crush the truck, the trailer and... well, not a pretty sight at all could develop.
NEVER even attempt this during any hour of the day going from Aspen and up to the Pass. Unless there is someone to stop traffic, totally, the risk is so severe of serious damage to your trailer, tow vehicle even if you are on the INSIDE heading to Aspen. IT IS NOT WORTH IT.
This section of Highway is not on my "bucket list" of things to repeat. I drive narrow blasted out roads in more remote locations and dread oncoming jeep or other traffic not spotted higher up throwing up a dust cloud on their way, up or down.
Pulling a wider and longer trailer around a curve... is pure suicide.
Other than that... we found it pleasant on top, took a walk around the observation area, took a photo of the trailer and sign, a photo of use posing next to the sign and... think of ourselves as the luckiest Airstream owners in the entire world!