Ian, I've given further thought to your question about how best to mount your CCL atop your rear rack. Here's what bubbled to the surface...

1) As I noted in an email to you, I've had good luck adding Ortlieb hooks and rails to the bottoms of friends' handlebar bags so they will effectively q/r lock into front racks or decaleurs. The trick is to line the bags first with Coroplast as George and I do, so the Ortlieb hardware has something to bite into and to stiffen the bag. Be sure to use the plastic-capped Ortlieb nuts if you add rails and hooks to the bottom of your CCL, as they create a smooth surface so vibration won't cause wear of the contents against the hardwear.

Unfortunately, I don't have photos of my conversions ready to hand, but you can get the general idea from other's efforts with HB bags shown in these two links...
https://theradavist.com/decaleur-hack
https://www.flickr.com/photos/88336152@N00/16567687779/
In this case, the rail-mounted hooks under your CCL would engage the rack crossbars. Three-four hooks and two rails would do the job for you, I think. It is worth noting the Ortlieb hardware creates a labyrinth seal when tightened, so you would have no fear of localized leaks.

2) You can also mount one of your panniers atop your rear rack, provided it has locking mounting hooks. I have done this with my Ortliebs both small (SportPacker) and large (BikePacker) and it works a treat; solid, reliable, and quick-release when you want so you can even de/remount the back in a moment to forage through it. See photo no. 1 below. It works best woth roll-top bags, but I've had no rain incursion with my drawstring-and-cap-top bags.

3) You really can fit a whole camping kit in your CCL suspended from the saddle's bag loops. If you need extra capacity or want to level-out the bag so your thighs don't strike it -- and if you have a rear rack -- it is pretty easy to place something you don't mind getting wet (i.e. tent or rain clothing in dry bags, possibly plastic/Crocs camp shoes) underneath the CCL. It all depends on the vertical gap between the bag loops and your rear rack.

See Photo nos. 2-3 of this setup on my gravel bike (since fitted with a sus-seatpost, it works the same). When it rains and I'm wearing my rain clothing, I just swap the tent (under the CCL rain flap) to the rack-top, replacing the blue clothing bag under the CCL. Unfortunately, this setup is not yet q/r...working on it!

For those who wonder if such a small touring kit is possible to fit in a CCL, you can view the contents in Photo no. 4.

Best, Dan.

EDIT: George, I have run half-step and granny gearing on five of my bikes since 1977; my preferred choice for derailleur touring bikes!

Yesbut...

! 

True enough, but I loved me that honey color! The one in question is a custom job once offered by Rivendell Cycle Works back in the day, made with (good) chrome rails, large hammered rivets, and the extra-thick leather I prefer for sustained long-distance riding.

It darkened a little with (red) Proofide, but still stayed on the lighter side.

Photos show how much more robust and expedition-oriented my 2012 Nomad Mk2 is than a more traditional tourer like my 1980 Centurion ProTour.

Last photo shows a tensionable sling saddle I intend for a drasienne (balance bike with Fred Flintstone drive) project I'm doing. A couple years ago, I was able to paddle (not pedal) for 30 miles on a less ideal saddle for the purpose, now thinking I could do more with the sling...no leather treatment needed!
See... https://fr.wikipedia.org/wiki/Draisienne

Best, Dan (...who loves bikes in all forms; saddles, more specifically)

There was once among the British working classes an equivalent to the American Dream. It wasn't about being rich, necessarily, as much as doing something right for the sake of doing it right, passionately. Imagine some chap with a small shop today sponsoring a rider in the Tour de France. It beggars belief.

Does anybody else look at that frame in his hand and consider the
wheelbase a bit short? Or were racing bikes that short c1950?

The photos in the version you found are better. Thanks, Dan.

Obenauf's, definitely. Widely recommended by American cyclists of the Sheldon Brown vintage, but not available this side of the Atlantic. Thanks, John.

Mike, on this forum some years ago, I expressed some mild disappointment that a Brooks waxed canvas seat cover wore rather fast when I sat upon it in the rain, and was told one isn't supposed to sit on it. I bought a plastic shower cap instead and sat on that when cycling in the rain.

Wonderful, Andre!

More here...
https://www.msn.com/en-gb/society-culture-and-history/history/war-hero-and-legendary-sheffield-bike-builder-who-lived-the-life-of-10-men-remembered-in-new-book/ar-AA22Ke0X

Best, Dan.