You guys are fortunate that the primary access threats seem to be from new riders, that simplifies things. Not all areas have that advantage.
Regarding helmet use, experienced guys (3 yrs+) have been far more likely to suffer severe injury, 65 % vs. 17 %, (including brain trauma, one of the more common types of severe injury) than newbies (<1 yr.). More at:
http://fksa.org/showthread.php?t=4125
By all means suggest new guys wear good lids, makes sense. But at the same time please keep in mind who has been carrying the greater risk for sometime.
You are doing a good job getting organized and generating a productive flow of ideas. Well done.