Thborchert
Unless you wish to pay Signature for handling I suggest that you telephone SOU Airside Operations (+442380627102) and request prior permission to land (PPR) and indicate the length of your stay on the ground. If you obtain prior permission from Operations you will not be charged a handling fee.
Operations are open 0630-2215 UTC Monday through Friday, 0630-2000 Saturday and 0730-2215 Sunday. It is best to request approval as soon as possible. Operations only accept a limited number of requests, which are subject to available parking stands. If they cannot issue approval (and a PPR number) you will have to request handling by Signature.
Best of luck!