There is no overnight parking on the summit or the highway. You could take the train halfway up, get off and walk another 3ish miles to find a high spot. Of course you'll have to walk back the day before the race and the whole one way train thing is tricky. I'd suggest going to a high altitude campground nearby (some listed in a previous thread) where you can essentially car camp and 10,000+ feet. For example, the campground at Kite Lake in Alma is essentially at tree line and you wouldn't have to walk but from your car to your tent. Pikes Peak is not the best camping mountain, especially if you're trying to save your legs.