That's what I was thinking would be most reasonable, I need to find a volunteer to build a custom loop on bifurcated with ITX GPUs when first article is done.
If you contact EKWB, let them know who you are & the company you represent, I am sure you could get them to make a custom version of this water block fittings terminal
I do believe this very same terminal was originally a custom piece for a SLI dual single-slot GPUs (ITX even, if I remember correctly, GTX 970s...?)
For use in the Sliger G, without having to increase the GPU chamber width (and adding a good bit of empty volume) I would see plugs on the four existing ports & two of the swiveling 90 degree fittings mounted thru the top, set for parallel flow...
Keep in mind you would have to attach the tubing & QDCs and fill the blocks / terminal assembly after the blocks were mounted to the cards...
But you would have bifurcated GPUs in the Sliger G, with the semi-custom AIO-esque water cooling solution from EKWB (unless you go for a X299 build & use the highly recommended Bitspower monoblock)...
8c/16t HEDT CPU power, 64GB DDR4 RAM, a 2TB NVMe RAID 5 array, and bifurcated SLI'edTitan Xp GPUs in a 15 to 18 liter (?) ITX specific chassis, all under water...!?! ;^p
Picture it; the Sliger G chassis, stuffed with the following:
ASRock X299E-ITX/ac motherboard
Intel i7-7820X (8c/16t) CPU (get one from Silicon Lottery for that delidded goodness)
64GB G.Skill DDR4 RAM (4 @ 16GB SO-DIMMs / 3200MHz / CAS 14)
Three 1TB Intel 600p M.2 NVMe SSDs (in RAID 5 with the add-in VROC dongle from Intel)
Dual Nvidia Titan Xp GPUs in SLI
Silverstone 800 watt SFX-L PSU (80+ Platinum rated)
For cooling, the following:
Bitspower monoblock for the ASRock X299E-ITX/ac
Dual EK-MLC FC1080 GTX Ti single-slot water blocks (they work with both the reference model 1080 Ti & Titan Xp cards)
The aforementioned semi-custom terminal
Two EK-MLC Phoenix 240 radiator core modules
Thermal Grizzly Kryonaut TIM for the CPU & GPU water blocks
Reuse the tubing that comes with the various water blocks & radiators & slap some 90 degree fittings on the radiators to cut down that tubing bend clearance issue...
You could plumb it all (CPU & GPUs) together in a single loop; or you could use the cabling available for EKWB to attach the pump & fans of one 240 radiator unit to the GPUs & attach the other radiator unit as normal to the CPU header on the motherboard for two separate loops, each controlled by the components it is cooling (I would do the latter)...
Add custom cables (don't forget the SATA power to the radiator units) & take lots of water cooling porn, er, I mean marketing photos...!