In England I have seen places where there are hiking-boot cleaning facility with water and brushes or boot-scrapers.
My thought is that these are all some form of amenity=cleaning_station which need to be expanded with tags denoting the exact features and purpose. water, compressed air, bug_spray, boot_cleaner . . .
For gaining acceptance I suggest a proposal for the amenity which also includes a description of future work which will suppport the amenity tag.