Jock,
Before you go to too much trouble worrying about which sporran to bring, it might be wise to check with your clansmen regarding the formality level of the events you'll be attending. It may be that you won't need anything very formal; on the other hand, your clan might want to "do it up big", since you'll be there from all the way across the Loch Mor.

And, to get the sporran back from your son, tell him that unless it's returned by a certain date, you'll iron creases into all his blue jeans.