A pedantic point (as it's becoming increasingly common and will probably become standard usage in a few years): the phrase is 'trouper' - as in member of a performing troupe - rather than trooper (military man).
Sorry to be a smart arse!
I see you pedantry and raise it to "super-annoying will you ever fuck off" level pedantry, but as it could easily be defined as courageous to take on all that dick, than either spelling could be deemed appropriate...."If the context has to do with courage,
trooper is appropriate. If the context has to do with cooperation, dependability, and the show business attitude of “the show must go on,” then
trouper is the word to use"