Right way to add a field to be used as a filter in Views with ranges?
This module might help: Views Contextual Range Filter

Module Page Description:


  Views Contextual Range Filter is a simple plugin for Views that adds
  the option to contextually filter not just by a single value, but also
  by range. Numeric, alphabetical (string) and list ranges are all
  supported. Node ids, user ids and even taxonomy term ids are all
  special cases of numbers so will work also. Range-filtering on the
  "created" (posted) and "updated" (last modified) node properties is
  also supported, provided you use the correct format as dictated by
  Views. So, YYYYMMDD for full dates or one of the shorter formats, i.e.
  year+month, year-only, month-only, week-only or day-only. You may use
  the OR operator (i.e. +) and the negate operator. You negate by
  ticking the "Exclude" box on the Views Contextual filter configuration
  panel, in the "More" section.