I'll admit I don't really understand the current ranking system, or exactly how ELO or something like it would change it. But, it sounds like you're trying to come up with a way to rank skiers based on how they ski against each other on a given day, as opposed to how they ski any given course.
I know it's been brought up before, but this is the way skiers are ranked for alpine ski racing. While the system on the whole is "pretty good" at accurately ranking skiers from all over the globe, it has a couple dangerous side effects:
1. To improve your ranking you need to go to events with better (ideally much better) skiers. This often gives an unfair advantage to athletes who can afford to "chase" events for points. Or even the lucky ones who happen to live where more of those events take place.
2. To improve your ranking you need to ski closer to or better than a higher ranked skier. This leaves the door open (especially at "backyard" events) for high ranking skiers to ski below their ability, artificially elevating the scores of lesser skiers.
Bottom line; there is probably no system that is perfect and people will always try to bend/leverage the rules to their advantage, and while it sucks when people get ahead of you unfairly, hopefully the system separates the skiers who can get a good ranking from the ones who can ski a good ranking.
my $.02