These 10 meter cables (and F/F DP adapter) work perfectly for me:
https://www.amazon.com/dp/B00V7NOST8/ref=cm_sw_r_cp_api_i_milyFbCG2DTYJ
https://www.amazon.com/dp/B00YFPM2CU/ref=cm_sw_r_cp_api_i_LjlyFb82TG4C9
https://www.amazon.com/dp/B01FQ88CHS/ref=cm_sw_r_cp_api_i_oklyFbQ7BC2HC
This setup has worked perfectly for me the last 2 years.
For 33ft/10m , just search for equivalent for the length you want.
https://www.amazon.com/gp/product/B00V7NOST8
The 8KX works for me with a 10meter (33 ft) optical display port cable and the same coupler that you linked. It could depend on the output strength of the displayport on your GPU whether you would need an active repeater vs the passive coupler. Can you get away with a 30 ft cable rather than 60ft? I think your chances would be much better with the 30ft. This is the one that worked for me.
I bought cables from Amazon that work perfectly. At work but message or reply and I'll look it up when I'm home. Total was $180 or so I think, so they were not cheap, but much better than $600 and no issues.
EDIT: These are the things I bought. Still working without issue after ~300 or so hours of use.
DisplayPort repeater ($20) https://smile.amazon.com/gp/product/B07D949F59/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
10m DisplayPort cable ($80) https://smile.amazon.com/gp/product/B00V7NOST8/ref=ppx_od_dt_b_asin_title_s02?ie=UTF8&th=1
10m USB 3.0 cable ($37) https://smile.amazon.com/gp/product/B07QDXJR9Z/ref=ppx_od_dt_b_asin_title_s03?ie=UTF8&th=1