"There were even three-color cameras that could compensate for the subtly different color sensitivities of early panchromatic emulsions by altering the shutter speed, though I don't know if Prokudin-Gorskii had one. Obviously, these cameras are pretty obscure now (though they were made into the 50's for some applications, apparently,) and my chance of ever getting one is less than zero."

The "one-shot" cameras had a single lens and shutter, they did not and could not, alter the speed for each film. The 3 sheets of film were at varying distances from the shutter depending on the color, thus wavelength, of the light to be recorded. They were very heavy. My 2.25x3.25 probably weight 20+pounds. They were intriguing cameras, and I always used a tripod. That was a really long time ago. I sold my camera when I went off to the university in 1945. Would I like one again? NO.although the dye transfer print made with the negatives were unsurpassed in beauty, they were a real PIA.One error near the end of the process, and you started over.
Sadly , I don't even have a print from that period in my life.