It was done today at Hickory Glen in Commerce as the MiSCA youth riding club held race number one (not sure how many are slated) and yours truly patrolled with a handful of others. I did witness a few tumbles but no one needing this pedaling St. Bernard to assist them.
As far as the social distancing, the racers/riders were told ahead of time to arrive 30 minutes before their departure time (chip timed - riders started separate about a minute apart) and leave the park once you finish. No lingering. Most parents (lot of helicopter parents at that) were masked up with very limited clustering so a gold star to the group putting it on under the circumstances.
Trail Head