On the topic of doing it yourself with aluminum rods and bars, it is my experience that the bar and rod stock that I buy at the hardware store is much more flexible than the metal parts that come on manufactured parts. 

Thus, my home made stuff is often weaker with lower weight capacity than commercially made components when using aluminum.

Maybe. I think the chap that made and sold these Lord uplifts probably compensated for any possible material weakness by using thick plate and rods. The uplift and the support that fits to the saddlebag weigh over 400g, nearly as much as the Tubus Fly steel rack.

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

George, that support in your first photo consists of the hoop connecting the two side plates of an original Blackburn Lowrider front rack. The connectors are sourced from an original (Mk1) Tubus Cargo rack (rods and adjustable tilt-plate, around 2007), a reflector bracke, and a piece of aluminum 90° angle. I found the same photo back in the day and made one using the same parts!

It worked well enough in concept and was stable, but the aluminum rod hoop was unnecessarily long and began to show signs of stress at the clamp. Also, it wasn't compatible with my rear pannier rack, so it didn't remain in service long. A good try, though, and top marks to the original innovator for repurposing existing parts!

The "handlebar bag" under-bag support on the seatpost is really clever, George.

When Forum member JulianK kindly gave me his old CCL, he included a Karrimor-style uplift bracket that engaged my Brooks saddle loops. It released quickly and easily, but I largely stopped using it out of concern larger loads could apply a lot of torque to the saddle loops, especially on bumpy roads. That started me noodling for something more solid, like the billet Q/R I described above. I really must spend some time out in my metal shop to bring it to reality!

I bought Thorn's extended T-bar uplift back in...2011, I think. It used machine screws and acorn nuts at either end of the cross and the idea was you could leve the CCL's leather straps a bit loose and so ease them over the acorn nuts when you need to quickly de/mount the bag. It worked but wasn't as stable as I'd hoped.

I also tried the nylon boat cleat trick...bolting the cleat through the bag and into the hardwood dowel. Undo the lower seatpost strap, give it a little wiggle, and the cleat's crossbar slipped between the saddle rails, yet was secure otherwise. Unfortunately, it tended to rattle unbearable on rougher roads and the bag wiggle a fair bit as the cleat's nylon crossbar wiggled back-and-forth despite the lower securement.

Best, Dan.

Carradice saddlebag with Lord uplift. ...
...
... On the other hand, this uplift puts the bag a bit higher up and a fair bit further back, giving me more room for my thighs than with a saddlebag attched to saddle loops and seatpost.
...

I did not like my Carradice bags hitting my legs.  I have made a modificaiton on my bikes where I can use the Carradice straps on saddle bag loops or on my Conquest saddles where there are no bag loops, but springs that I can use as a substitute for the saddle bag loops.

I use a threadless stem, shimmed to fit on the seatpost, and a wood dowel to push the bag further to the rear at the lower part of the bag where the strap is.  I also use a longer strap, in this case use a leather toe clip strap.  First photo below.

And since I am showing photos, I have commented before that I put a piece of coroplast inside the bag to give it more structure and better shape when partially empty, second photo.  The coroplast is simply bent into a U shape, not physically attached to the bag.  Thus, if I have one small heavy item in the bag, it does not sag.  I initially tried paper cardboard, but when I was happy with the result I replaced it with coroplast which retains shape better when damp or wet.

The bag shown is a Pendle.

Final photo. Another view of the uplift without the saddlebag.

Carradice saddlebag with Lord uplift. I have posted this to give an idea of one way of fitting a saddlebag to a saddle without loops. I could probably have made this myself, but at the time it was easier to buy this uplift. It gives a quick release saddlebag, but the uplift itself stays clamped to the saddle rails.

Two hooks on the upper part of the uplift engage two Allen bolts that are screwed into the cylindrical aluminium rod that replaces the original wood dowel that comes with the saddlebag. A flexible plastic clip replaces the leather strap that stabilises the lower part of the bag, this allows the bottom of the bag to release from the aluminium rod on the lower part of the uplift, it is then possible to lift the bag forwards and upwards to disengage the Allen bolts from the hooks to remove the bag.

I have used this system for about 3 decades, predominantly on lightweight bikes with no racks. It works quite well, but one downside is that I tended to chafe cycling shorts on the hooks on the (rare) occasions that I rode without a saddlebag. On the other hand, this uplift puts the bag a bit higher up and a fair bit further back, giving me more room for my thighs than with a saddlebag attched to saddle loops and seatpost.

The first 3 photos are of the saddlebag attached to the uplift, which has been removed from the bike saddle.
The 4th photo is of the bag which has been removed from the uplift.