Hi Mary
I have to think about the points that you raise. At first blush... It seems that all of these contingencies address the racer who's attitude is ... Hey I'm buying a service! rather a racer who is supporting the club he belongs to or a member club in the region.
Seems to me a statement to the effect that a regatta organzer will refund as much of the registration fee as possible will be sufficient. Actually, I think it is implied in the context of a club setting hosting regattas.
You summarized the issue this way.
The big challenge is to eliminate what may be perceived as a "risk factor" for sailors who pre-pay. Like, is there a situation where I might pay in advance and lose my money, whereas all the people who were going to pay at the last minute on site are saying, "Boy, am I glad I didn't go to that one"??
If a sailor thinks it's too risky to preregister (for whatever reason) and he might loose a few bucks ... he simply chooses to pay the premium on site.