Hello,
Personally I would not screw brackets to the caravan, as holes could mean water ingress. Our pouch awning came with some sucker clamps, but it also had an internal awing strip that you could attach another sort of clamp to. See similar here http://www.towsure.com/product/13374-Pyramid_Awning_Pole_Attacha_Pad I opted for these at a few pound each and required 3.