I know you directed this to Jama, but I'll chime in to say that you will still be at elevation for a week or so in Colorado (maybe less depending on daily mileage, but at least a few days). From Astoria you will be about 2000 miles or a little more before you are out of the higher elevations. Your 25 day number sounds a little optimistic. You'd need to average the high end of your estimated mileage with no rest days, half days, waiting out snow, mechanical problems or other setbacks. I would suggest allowing more like 35 days and if you manage 25 so much the better.