Hi PB.
I remember all this being the rage about thirty years ago, but, like the exaggerated chipping from a decade ago, it fell out of fashion. Never really gone for the scale effect theory (or excessive chopping) myself, too many variables, but if I was going to try it I would do the following. Find a picture taken from the distance I was trying to mimic, taken at the time of day and weather conditions I wanted to copy (this is important, colour changes with weather and time of day) and just copy the colours I see. you will need to learn colour mixing, but that just takes a bit of practice. I really don’t think there is a set value you can use, but if there was it would probably require a grey rather than a white addition as you need to desaturate the base tone rather than just lighten it as that is what atmospheric dust and moisture do to colours. In fact, copying a decent picture to replicate the effect you are after is usually the best way forwards, rather than esoteric theorising.
I am really not trying to be negative here, it’s just my take on it. If you want to go down the scale colour route I will help as much as I am able, and I’m sure the rest of the guys on here would do the same.