My bachelor party was a trip to the range. Couple of the guys on my side of the church were under 21, I am not really a strip joint kind of guy anyway, it worked well for me.
Besides no booze and not too much competition (both great ideas), I would add: 1)someone designated to clean the groom's guns during the honeymoon
2) bring lots of different guns so everyone can find something interesting to shoot.
My front stuffer single shot black powder pistol turned out to be the most popular gun at the party - therefore my point number one above.