I would suggest the Range slider for this purpuse. It uses the “BETWEEN” operator on database level – but it still does not exceeds the selected range, it is strict. So if the range is 1 – 10 and the user selects 2 and 5, then values between 2 and 5 are considered as match – there is no additional boundary.
I would probably make one range slider for the latitude, other for the longitude, but both latitude and longitude must be a separate custom field as a numeric value (no spaces, no other extra characters) – otherwise it will be recognized as a string by the MySql database.Best,
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