Sounds complicated and wicked. Having cpu/gpu loops in parralel sounds like a good idea. You can use a 3rd separate connection to the reservoir that goes through the refridgeration unit. Thats going to be alot of water in the loops though and you gotta be careful with the condensation. I suggest going a little higher in temps to stop the condensation if you in north QLD during summer condensation will build up really easy. Same with other parts of australia due to the humidity. And due to the amount of cooling temps under load won't change much. As well ryzen 3000 doesn't overclock very well, so temps are fairly easy to control. Good luck mate it will be an awesome build.