Pretty much any ride I do around here (northern California), there's about 1,000' of climbing per 10 miles, so your ride exceeds that by a fair amount. It's almost impossible to do a flat ride here. Good luck on your double century. I've done the Davis Double (similar to the Hemet Double) a bunch of times and it's a great feeling of accomplishment when you finish. That said, I did a much harder ride a couple of years ago...the Markleeville Deathride...130 miles and 16,000' of climbing. It's the climbing (and the altitude) that gets you, not the miles.