I really like the look and utility of the Smuggler but still don't know if it will work with the excellent Bygdawg rack. If I were to get serious about considering one a ride down to Hollister to check fitment could be in order.
Yea or nay on a Smuggler then stop at Gizdich Ranch for a tall apple pie would make the trip worth while. A whole pie fits in a pannier no problem. There are two panniers.
Regarding the pads – they may not be able to make the thin pad thinner but they could probably stack pads as appropriate. I've never used a backrest so a pad on a Smuggler would be purely to protect the paint.