Yes I got it. The plan is to put the (fork) mount on a pier, so we wouldn't need the derotator.
The main issue I see is to find a suitable CCD nowadays. The 16803 are not made anymore, and the closest thing I could imagine putting there would be an IMX455 sensor - albeit probabily needing to go bin 2x2 the whole time. Adding a CenterLine filter wheel for round 50,4mm filters would give us a chance to have a total of 12 filter spots (LRGB, Ha O3 S2 plus Photometric BVRI plus "dark" one instead of the shutter).
Realistically, we won't go for a bigger than 20" scope, simply because the price delta is huge and we would have to charge far more per hour for a bigger scope.