I could barely support 50-60ft at 1080p over physical hdmi for some noc video walls I built for a customer, 4k is likely going to be worse without an active component chip to the extension cable. Quality of the cable is a big part - to get length, I required the use of specifically 24ga wire in the cable, which was quite thick, but not a biggie as most was in walls. I got this up to 75ft, but again only 1080p, not 4k...
My suggestion is look at 4k over lan repeaters ala HDBase-T. They are out there, but pricey(er) for 4k - check
monoprice. I've used 1080p units like Just Add Power units for video walls, but requires some automation around it too for more than one. Just a single display should be easy to extend over copper with some hdmi adapters at least.
-mb