... The addition of D-rings on the saddlebags by Carradice is good, it's a hack that many owners did themselves and I did it to my Camper to help carrying the bag when off the bike....
Yeah, I added D rings too, you can see them in my photos. I used a short piece of nylon strap on each one, hand sewn to the inside of the lid. Can use a shoulder strap to carry it.
I have not been very impressed from what I saw on line about the bag mounting systems that Carradice offers. Thus have not tried them.
Several months ago I decided to order a Camper too. Have not used it yet, but if I ever want to do a credit card trip, I think it would work well for me. I pack heavier than you do, so I think the Camper would work best for me for credit card tripping. I was tempted to buy green, but in the end stuck with black. I think it would work nice on my road bike or rando bike.
The fabric on my new Camper appears to be treated differently than on my older Carradice bags. I do not recall when I bought my Nelson Longflap or Pendle, my bike tour photos tell me that I used one of them on a tour in 2014, so my older ones are at least nine years old.