You can't completely mitigate the risk of accidents, even with all kinds of range supervision. I've seen that proven during many days on the ranges in active duty and guard service. I think there should be a happy medium, because part of the fun of shooting with this group of people is the lack of rigidity. I agree we should have some ground rules consisting of basic firearm safety rules, but even some of the rules discussed won't work, such as having the action open (some rifles have no bolt hold-open feature, like AK's), and handling of firearms on a cold range (due to the fact one large fun fact of our gatherings is indeed showing each other our guns). The size of the range also makes that last one iffy, such as shooting at Swingsets place, as the firing line is very close to the cold line.
I do think a common sense sign should be posted at our gatherings, and that people be asked to abide these simple rules (whatever they end up being). Swingset said it best in saying "If we're observant, especially with new faces and new shooters, we will get along just fine."