Some rides have offered a best vet score award in the past from time to
time.  I put up a cash prize for one one year at the New MExico Renegade
ride.  I dont know who won, as i left the night before the judging was to
take place.
This however is not a very practical approach, as it would require the
veterinarians to possibly have to judge  a hundred or more  horses, hence
the current system of cutoffs and handicaps.  It isn't completely  fair to
the horses or the riders. But it certainly isnt a total ripoff of the
heavyweight rider  either.