AdVerburg
Have a look at the definition https://wiki.openstreetmap.org/wiki/Tag:barrier%3Dentrance 
It says that this is een opening in a lineair barrier, not mentioning entrance or exit.
So what you did is correct, 
however you positioned the southern entrance very near (not on) the fence (in other words there are two nodes nearby).
Aside from that, the (oneway) lanes on the parking area could be drawn, so routers (and drivers) can find their way out. The oneway direction of the northern serviceroad should be changed. Also the facilities like waste disposel (showers maybe, I could not see) can be mapped.
An other tip to get a faster response: post your question on the Belgian forum: https://forum.openstreetmap.org/viewforum.php?id=29 or on the Dutch forum: https://forum.openstreetmap.org/viewforum.php?id=12