An AIP supplement last year amended all operating hours.
Let me try out the new picture uploading tool that PPRuNe added...
Attachment 5149
Attachment 5150
As the Botswana regulations don't allow VFR night flights and there are no instrument approaches or late scheduled flights into Kasane, I assume that is why the airport closes so early. Of course it may be possible to pre-arrange a later arrival (at a cost).