I took the first attached photo about a decade ago.  Someone made this bracket to support their bikepacking type saddle bag.

And the second photo shows how I put my Pendle bag on my road bike, I used a shim and a long threadless stem, plus a wood dowel (sprayed black) that my saddle bag attaches to.  My Brooks Pro lacks the saddle bag loops, so the Pendle straps wrap around the dowel.  I used a 5/16 inch diameter aluminum rod to support my bag weight, but if you wanted to support the weight of a packed Camper I think the system I am showing in this second photo would not hold the weight, that was why I showed the first photo.  It was pretty easy for me to bend the 5/16 inch aluminum rod to get it to fit exactly the way I wanted, but I only tested it with two kg of weight inside the saddle bag on a bumpy ride to see if that rod was sufficient to keep my Pendle from rubbing on the tire.  It holds two kg (two water bottles, one liter each for weight in the Pendle for my test).

In other words, you could build up something to support the weight under the saddle bag, and a separate bracket like mine using a threadless stem (plus seatpost shim) to put the saddle bag straps on since you would lack the saddle loops.

But before you try to build something like this, I am tall enough (about 6 foot) that my saddle has a good height above my rear 700c tire, if you are shorter, you might not have the height you would need for tire clearance under the bag if you attached your bag to a stem mounted on the seatpost like I did.  Note the third photo, I have the tire clearance I need.

That sounds like a simple but effective solution. I'll look into that. Thanks.
I already have some male and female velcro straps that I've used to secure the CLF's base across the rear rack so I might be able to modify that set up.
Thanks again

Dan, that sounds like a very useful project to pursue. I'll look forward to seeing the prototype in due course.

I really like the CLF but I've rarely used it. That's primarily because it is awkward to take on and off if you're not using a Carradice bagman rack, more so if you already have a Thorn rack fitted. I think I last used it when I cycled down the west coast of Eire and carried my tent in it; leaving the CLF attached.

Rok-straps might work well to hold your bag longitudinally on the rack.  They come in two halves and each half has a loop at the end.  You would feed the strap around the side of the rack and back through the loop, do the same with the other half of the strap on the opposite side of the rack, clip the two haves together and then tighten.  The straps and clips are flat material and strong, and one half is elastic so they stay tight.   Two straps needed.  Have a look at their web site.
Safer and more secure than bungees with hooks.

My rivet are rusty because i stored my bike in a garage who sometimes there is a humid atmosphere .. and probably also  the contact with my Cotton blanket 

From 1980 to 2021 my garage was quite humide, with condensation in winter dripping down from the (thin) corrugated roof. So I tried to park all the bikes in places where the drips didn't fall on them.

Just before the 2021 COVID lockdown I hired a van and bought the material necessary to insulate the inside walls of the garage and under the roof. It took quite a lot of time and effort to do the work, but the garage is much drier in winter now. It's better for leather bike saddles, but also for steel tools and some of the other stuff I keep in the garage. Even so, leather and tools kept in my garage still need a certain amount of maintenance, but not so often since 2021.

My rivet are rusty because i stored my bike in a garage who sometimes there is a humid atmosphere .. and probably also  the contact with my Cotton blanket