I have this 'remote' cooling stack which is an old PSU running 2x D5s and many fans. I have Koolance quick disconnects at basically every waterblock across both computers on this loop (2x GPU, 2x CPU, sometimes a RAM block). I also have the same 2x D5 pump block on my gaming PC across the room. The pumps all run at 100%. It won't hurt the pumps. I have a pressure release valve on my reservoir in case of gas pressure since there are so many failure points on this loop.
Oh, and to solve the PC being removed from the external loop simplify it by just using quick disconnects and buying one more set create a return line from the outlet on the PC right back to the inlet.