Wear the cream hose if you like them. Wear the fly also, if you wish. I've been to five black tie Highland events in the past year alone and saw plenty of cream hose and a surprising number of fly plaids as well. I do not understand the fear of looking like you rented your outfit. If you have a well-made PC and kilt, and a nice sporan you will look great regardless of your hose. Wear what you like and be proud to be kilted!