Hi everyone - I'm new here so I'm hoping I posted this in the right section. 
 
I am currently in the process of building my wedding present build (well technically it's two systems)
 
System One:
CPU: AMD Ryzen 9 3900X 3.8 GHz 12-Core Processor
Motherboard: Gigabyte X570 AORUS XTREME EATX AM4 Motherboard 
Memory: G.Skill Trident Z Neo 64 GB (4 x 16 GB) DDR4-3600 Memory
Storage: Corsair MP600 Force Series Gen4 2 TB M.2-2280 NVME Solid State Drive
Video Card: 2 x EVGA GeForce RTX 2080 Ti 11 GB KINGPIN GAMING Video Card 
Power Supply: Corsair 1600 W 80+ Titanium Certified Fully Modular ATX Power Supply 


System Two will contain a Mini ITX build for my wife located in the bottom of my Phanteks Enthoo Luxe 2. 
Will likely have 16GB of RAM and a GTX 1080ti and a 512GB M.2 SSD.
 
My question is this - the Phanteks PSUs that can power dual systems only go up to 1200W. I'm not going to use that as with 2 Kingpins, I HIGHLY doubt that's a good idea. Referencing the xdevs posts, I've decided to go with either an EVGA 1500W or even the Corsair AX1600i. 
 
I want to use the Phanteks PSU splitter, but I'm worried about it so I'd thought I'd post here. I can't fit a second PSU in the Luxe 2 without modding, as I'm using the second space for the ITX build. The idea is to use this PSU splitter with both systems. Would you recommend this? Any advice is greatly appreciated!