I arranged the parts to get the base plate as low as possible to allow the interior to still be used (first two photos) and making it easier (closer) to screw in the mount. But, if you're not using the interior (and I still may not), it doesn't matter.
A happy accident... the space left between the mount plate and window was just right for the original turret window frame part to still be used. It fills the gap and hides the four screws in the center.
I do like the thicker threaded rod you're using.
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