"unless the skill of circling below 300 ft without crashing is a key skill that we are trying to measure."

I would bet no one would say this is a skill anyone is testing in a contest.

I had very good training by a Hall of Fame pilot
1. Aren't we supposed to be over the field we selected and able to do a complete pattern, at pattern altitude?
2. Every off farmer field landing I have ever done was the first time I have landed in that field!

So the time you need to look at it and set up is not happening below pattern altitude - we do not have/allow 300 ft patterns at our club - matter of fact we don't have/allow 500 ft patterns either

I do like Andy's suggestion, as it has more teaching power - circle below a given altitude anywhere in the contest and explain the "why this was safe" to the room full of pilots the next day.......... Ouch!

Been there done that - will try to never do that again!

WH