We're all human; one can miss things on NOTAMS.
You are assuming all pilots check!
Not much excuse when three NOTAMs are out about it.
No-one has mentioned the freephone number. If they can't even phone the 0500-354802 number for free....
Given good weather, IMHO I'm afraid there is NO CHANCE of keeping everyone out of that area. I don't think you realise how many people don't have a clue about checking NOTAMs, 0500 354802 etc, AND basically really don't care - it's going to take a lot of prosecutions or similar, highly publicised, to make these pilots do it!
I'm thinking of starting a log of how many pilots come for their 2 year checkouts and DO NOT know how to check notams or know about 0500-354802. I use these JAR hours to show them so it is getting slightly better locally but it is worrying.