Bo --
In looking for aerial photography, did you check with any of the local aerial surveying companies? If they are like my employer, the County (often the Assessor's Office) may have hired them to fly the entire County, and they may still have the original negatives. They should be able to sell copies of the images to you because the images are public domain, having been flown for a government entity.
Since you know exactly where your site is, they can print up to a 20X enlargement, which will show grain that is not too excessive. If still seeking the area, you could order a paper contact print, which would still have incredible detail (considering the scale). Keep in mind, most such photography would have a scale on the negative of 1"=2,000' or 1"=1,000' (+/-). The negative is 9"x9".
Other possible sources for aerial photography would be the USFS, US Army Corps of Engineers, and the state's Dept of Water Resources.
A warning before anybody runs out to do this... it won't be cheap. Since it is a custom photo job, there will be a minimum charge (ours is $75), and an enlargement will often exceed that amount.
Wish my employer had some Colorado photography...