After having cut a hole in the wall to peek into the crawlspace, it seem rather feasible to relocate our 3-prong dryer receptacle to a new location by running new 4-wire cable all the way back to the main panel, by disconnecting the current 3-wire cable at the panel and at the receptacle, attaching a rope to one end and pulling it out through the other end, which would seem to be feasible since the existing 3-wire cable is unsupported as far as I can tell. The 1940's crawlspace is dry, no evidence of mold or rot.
I can't get in there to support the new 4-wire cable, but could probably figure out something to keep it off the ground. I read elsewhere in a discussion about crawlspaces that exceptions exist allowing no support if you have to fish or snake.
Is that true? Would this apply to my crawlspace run? What is the code section? Does it change the type of 4-wire cable that is allowed?