First, I would like to say I am against limits of any kind at the Imperial Sand Dunes Recreation Area.
Just like you state that a ban on drinking would be impossible to enforce, so would a ban on the amount of people be impossible to enforce. If there was only one way in and out of Glamis the enforcement might be possible; but there are many areas in and out.
Also, if you set a limit of say, 200,000 people, who's to say you wouldn't get 50 non-violent "good people" and 199,950 violent people?
How did Glamis/ISDRA get to this point? Through the Bureau of Land Management's mismanagement of the sand dunes. Each year, it seems to me, the BLM forgets (on purpose?) that Halloween and Thanksgiving are going to be rowdy (they are the first long weekends at the ISDRA). More law enforcement officers, or LEOs, are needed on those holidays.