I just mounted some Apache cases sold at Harbor Freight (model 4800). Then on Ebay I found coyotetrips.com that had a great mounting system. You can carry your luggage in a motel but more importantly remove for servicing the bike.The cases work great for my needs but are smaller at 24 liters of capacity. At 69 I was interested in being able to easily throw a leg over my bike. All the Caribou and other options force you to mount almost level with the pillion seat. this makes sense for mounting additional dry bags over the top for sure. They are big and wide to get that 35 and 45 liters mounted up.
Total cost was $200.00, I did have racks on the bike that I bought used, Givi?
I accomplished what I was after the total width 33" and 2-3" lower than pillion. Can carry rain gear, a few tools/tire items and heated gear along with clothing for a 2-3 day trip. More than that I have a tail bag that I hate to use.