I have been trying to do something similar. I have a separate php function that does the geocoding (lat, lon & geohash). Yes, I prefer to use geohashing versus “great big circle” sql algorithm. I have done php and other dev for the past 10+ years but this is the first wordpress.
My thought was to create a custom field for all this custom data but I have to figure out how to “save” it in the database for child sub-fields. Could probably do easier outside the “repeater”. Since no answer here on my question I have resorted to other tools and will probably wind up with a CPT in gravity forms instead.