Everyone in college English reads Walter Mitty because it is the shortest of all the required-reading short stories. Not for that reason, however, is it the stand-alone classic that it is.
It’s brevity ensures greater readership, certainly, but is more a testiment to economy of story as it is many stories within a story whose range transverse a broad spectrum of appeal. Also, more people are going to read it because it says a lot in a short space that a lot of people can relate to and then tell their friends. To attempt its replication in any way shape or form spacks of cliche. That you would suggest such a thing puts you back at the starting line in my literary mental game of mother may I… again! You must be having an off day, Mr. Wright.

2) You have to write a book about a frustrated adventurer, because that’s what you are.

You have to write an updated version of Walter Mitty.