Great blog and pictures!
Per your mention of boondocking locations near Aspen... next time in the area, especially if the Sept. timeframe, you may want to consider heading over into the Taylor Park area. This can be a mildly busy area in the summer with OHV vehicles, but the valley and surrounding area is so huge it almost doesn't matter. That makes visiting the area in Sept that much more special.
There are endless areas to boondock within 5/10 miles around the Taylor Reservoir area. Taylor Park is due south of Aspen however there is no improved direct road you can use to get to TP from Aspen so one must come from a different direction. Per your trip, you were north anyway, so from I70, heading south through Leadville to Buena Vista and then west over Cottonwood Pass. Cottonwood Pass is seasonal but is generally open until snow closes it. I was out in TP at the same time you were in Aspen and I take my 30' TT over Cottonwood Pass and it is a non-issue.
From the TP area, there is good access to get to Crested Butte as well as a lot of very small and unique mountain towns. South from TP is Gunnison and then west of there is an amazing area, Blue Mesa Reservoir with camping in and around. Further west is the Black Canyon of the Gunnison NP although admittedly, I have not been there. That gets you very close to Montrose which I'm sure you are aware is just north of the SW portion of the state with its own beauty.
