You can buy a short length of plastic for connecting the skirt to an extension cover for this area. Basically it has a channel both sides to take the awning beading and about a metre long. If you cut this a little shorter than the width between the skirt rails across the acrch. Then slide in half the skirt, add the channel piece, and then slide in the other half. When you peg the skirt pull it fairly taut so the channel lies horizontally across the arch. This works on my coachman stopping the saggy draughty effect, so maybe it will on the Bailey.