Guys!
STOP right here.
ICAO ans EASA minima prevail.
STOP trying to invent rules by converting height to distances etc.
Minima for EASA and most other authorities are for Cat1 : 550m. Rvr and Decision Altitude of 200 ft. But variable for each runway.
So as long as you have more than 550'rvr ( or 800 m) ( taking into account approach ban obviously) and see the runway or approach lights at your DA, you are legal to land.
There is NO CEILING limit!
there is NO requirement to interpolate, calculate or anything else than to follow the bloody minima depicted on your charts.