I see what you mean but when you consider how the various stages in the 282 are powered from each socket, you’ll effectively end up with a bit of a Frankenstein arrangement with single rail DR power supply feeding one channel and a dual rail non DR feeding the other.
It may be worth trying by using the FC2X, but in the conventional way
282 Upgrade 1 to FC2X Power out A via a SNAIC5. Connect signal out A to the 200DR via a SNAIC4. You could also power Upgrade 2 from Power out B….
….But I do wonder how well the non DR FC2X supply would compare to the single rail DR supply from the 200DR. I would save money and put it towards a Hicap DR.
Details here on how the various stages are powered from the Upgrade 1 & 2 sockets