Long ago one who was having orthodontia noticed these teensy rubber bands
used to increase the torture factor of the appliances.  Often used em to
tighten glasses whose frames had become long in the tooth.  Using one to
clamp the razor guard to the razor might work.  Or you could pony up for a
Rolls Razor.  Or you could use a suitable O-ring or duct tape.  Improvise,
adapt, overcome.

A hot shave with Wilkinsons Shave Soap and a fine pure badger brush at
sunrise can be an enlightening experience especially in the land of AZ high
in the Santa Rita's.  Westy provides the hot water, driver side mirror the
place to hang the towel and view the process so as to avoid inadvertant
severing of a carotid.

Tour report of the long march to Patagonia to come.