Oh I can feel and hear your pain Joe. Many years ago I made all of my pants, including jeans. One of the items I used was a Jean-A-Ma-Jig. Made it easier for the presser foot to travel over thick denim seams. I still have some Schmetz denim needles in my supplies, size 100x16. I think that they also make a 110x18 needle. I like Tartan's idea about exposed seams, it would add interest to the outsides of the bag. If I were to make one of your heavy denim bags I would line the handles to eliminate some of the bulk. Keep us posted.