Walsenburg, Colorado passed amendments to the 2015 IRC to be more tiny house friendly for homes on foundations. They waived minimum room areas and stairway regulations and reduced the requirement for exit door width: Walsenburg Colorado Ordinance No. 1092
Zoning regulations were made tiny house friendly in 2014: https://americantinyhouseassociation.org/tiny-houses-on-foundations-allowed-with-a-variance-in-walensburg-co/