i am looking into some of your suggestions with much attention.
my input setup is currently a DATAPATH Dual-Channel Display Port 1.2 Ultra-HD
through 1 channel, we are topping it at 3072x3072 at 60h (with 4' cable). 30hz over extender setup (cat6)
DP1.3 or 1.4 (or HDMI 2.1) would give us more room to explore higher resolutions or framerate, they just don't seem to be on the market yet.
i just learned about all these companies that make clone capture cards,might find something in there...
the search is on!