Well, I think that case isn't optimal for a custom loop water cooling... - not hopeless though...
If you don't want to remove the HDD cage to make some room, then your options are pretty limited... - I would go then with a closed loop system for the CPU... or, go with an external rad setup, then you will be able to cool everything in that system...
You perhaps can find everything you need for watercooling on the EKWB's website...