We would only be renting the larger room (that room comes equipped with it's own bathroom facilities for both men and women). To make it a non-smoking event, you would have to put out the invitations or notifications as "Non Smoking INDOORS" ... Smoking permitted OUTDOORS only (for this reunion).
To ask the actual ELKS if they would fore-go their smoking.. well, I would think they would answer with ... "Plan your event somewhere else" (I don't know this for sure... and I really do not think they would tell us this, but....). It is after-all their hall....their building... and a few of them would be there as their typical weekend night's event.
So......... I suggest to put in the invitations... NON-SMOKING REUNION - SMOKING OUTDOORS ONLY... and then let everyone else figure out what they need to do or are willing to do.