Great info mod-it. I'll have to pay more attention at the trail head next time. Were you seeing the same 2-3 yard difference at close and far ranges or just far?
If I went and shot it again knowing what I know now, i'd have a rough system to take 1 yard off for targets 32 or so yards or less, 2 yards off for 33 to 49 yard targets, and 3 yards off for targets 50 to 60.
Keep in mind, a lot of the shots were fairly steep up/downhill shots too, so my angle compensation rangefinders were having me take off a couple yards on a lot of shots as well. If my rangefinders said it was 45 yards, shoot for 43, then I'd have to dial more like 41 yards to not hit high.
If we shot ALL the targets at an altitude that had us hitting high, then I'd just back my poundage off until my sight tape was true again. But we didn't bother since it was only the first several targets that were a problem. Walking down off a ski hill dropped elevation pretty fast and we stopped hitting high fairly quickly, within 4 to 6 targets in. They had the targets pretty spread out, each course was only a 20 target course.
Just a somewhat wild estimation of elevation, but a google search shows the very top of hill is 6200', the top of the Gondola is 5700'. But then after going up the gondola we rode a chairlift back down in elevation to the bottom of chairlift #2, I'd guess the bottom of chair #2 to be around 5000' or so. So, we were shooting 20 target courses starting at 6200' and working back down to around 5000', give or take a couple hundred feet. I'd guess we stopped hitting high at around 5500' or so.