Norman, you've pretty much got it.
The piano goes on top of the organ, with a couple of pieces of 1x4 covered in toolbox tray liner at the back to give it a tiny forward angle. The organ's music rack is removed; the piano has a lip that catches into the lip on the organ that normally catches your music book. So the piano overhangs the organ nicely, and is very sturdy - sturdier than any folding stand I have ever used.
The keyboard amp goes on top of the Leslie when I'm in tight quarters, which is pretty much always. I run it a bit cockeyed to the Leslie so that I don't go deaf with the horn at ear-height.
Which reminds me, in this configuration I have to use a wedge-style damper pedal, I have a hole drilled in the front of the organ near the expression pedal for the cord, so it can go through the organ rather than around it.
Here is a photo I snapped while building the back to give you an idea:
I usually gig with the black Leslie. You can't see my piano amp in this picture. When I have the choice and we are putting everything through the PA, I like to put the Leslie on the organ side nearest the audience and furthest from the band... the idea is to get maximum stage-bleed to the audience without raising stage volume.
As I said before, I stand to play the piano and sit to play the organ. This works well, I'm lucky that I just happen to have the right length legs for this, as I cannot do the "Hammond Hunch" with my back. I would love to use a more traditional L shape and sit for everything, but there is not enough stage space anywhere I play to allow this..... and I am also not able to twist my torso or neck for more than a few seconds at a time, it causes inflammation of the nerves which control my fingers. Not good!
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Hammond: BC, M3, Split L111, L122 / Leslie: 51, 760 / Yamaha: DGX-620, PF-85
Follow my new band,
Dr. Bombay! We're going to be organasmic!