If you have 8 th tray it can be posible and easy to do it. But there is 1 question, what is the gsm of cover page. If it is too thick it may can't be fold it.
you will print 1st side of cover on d125 whic is 2. and 7. page. Then you feed same paper to c75 and print second side of cover. You will denify this job as a booklet (print on both side) add cover and done.
I do like that on a3 i don't know how it will react to special size of paper.
For providing toner melting you can can print the b&w side first then colored side secondly. I never had this kind of problem with xerox 4595.
RIP doesn't matter on this technic.
Depends on the RIP.
Your D125 can have a Freeflow (Probably can do it), a Fiery (Can do it), or just the embedded controller (Nope, can't do it),
Worst case scenario is you use the C75 to do inside and outside of the cover then insert it as a preprinted cover on the D125 and take the hit on click charge.
Or the C75 does the outside, then the D125 does the inside of the same sheet, then the D125 does the job with a preprinted cover and you take the hit on speed and workflow. (because you ran 3 jobs), you also have to hope the D125 doesn't melt the toner on the color side as it runs hotter than the C75 due to its speed
If you have the Fiery, you can simply do what you wanted and just print inside the cover as seen here
I believe, but am not certain the FFPS also can do a single sided cover.
I have a simple 8 page booklet. We print the outside cover on our C75 single sided onto 11x17.
We then need to print the inside cover plus the additional black and white inside signature on our D125 with the cover, fold and staple.
So it's pages 1-8, with pages 1 & 8 in color printed on the C75 and then pages 2-7 printed in black and white printed on the D125, folded and stapled.
If you select page "exceptions" to define the cover as single sided pulling from a separate tray as the body, the booklet option is not available. If you select the booklet creation option, then the paper "exception" is option is not available.
Is this not really possible?