• Step 1 -- The law is probably not overbroad since it seems fairly specifically directed at prohibiting only material of a sexual nature such as to be obscene (under Gulfport law).  It is probably vague (under Connally v. General Construction 1926) because of the undefined term "erotic setting."  (This decision could go either way with an appropriate explanation.)
• Step 2 -- Under Chaplinsky v N.H. 1942, this is the heart of the matter.  Is the picture obscene? (The appropriate category under Chaplinsky guidelines is #1)   The evaluation of this case (go down on the chart) involves testing whether or not the picture can be restricted as "worthless speech?"
• Step 3 -- Using the precedent case of Miller v California - test 1:  a shower scene does not seem erotic enough to be classified as "appealing to the prurient interest."  test 2:  Under Jenkins v Georgia 1974, mere nudity is not enough to be considered "patently offensive and, thus, obscene.  test 3:  Using the SLAPS test and the fact that the photographer is an award winner, this work likely has redeeming artistic value.  Thus, the work is not obscene and deserves 1st amendment protection. [ FYI.  Under level one there does not appear to be any danger (bad tendency is no longer the law) and no precedents which support a compelling state interest to balance McGahan's speech against some other state interest.  Free speech is the preferred freedom.  ]

   Resulting decision

• Due to vagueness  the law is unconstitutional (This could go either way with an appropriate explanation)
• The work is not obscene under Miller -- so (either way) McGahan's conviction is overturned.

Trudison v CIA

• Step 1 -- The contact language Trudison signed is not vague.  It seems quite clear as to what the "rules" are.  While the language is broad in that it restricts any material concerning U.S. Government Activities, since it is in a contract Trudison voluntarily signed, that question should probably have been raised long ago.  In any case, because it restricts discussion of activities but not opinions on policy the court would not overturn the injunction based on over breadth.  (This decision could go the other way if you present a good justification.) 
• Step 2 -- The book in question is certainly "worthwhile speech" since it deals with matters of clear public concern in the administration of government activities and there is no indication of lewd, obscene, defamatory or fighting words being at issue (as required under Chaplinsky).
• Step 3 -- The appropriate level one test is #2 - Balancing.  Is there sufficient government interest in national security to justify prohibiting the book?   Under Snepp v United States 1980 the USSC affirmed that secrecy agreements signed by government employees are binding and First Amendment protections cannot save expression that is restricted under a valid contract.  In essence, the court in Snepp confirmed the lower court decision in United States v Marchetti 1972 that treated such conflicts as matters of contract dispute NOT free expression.  

   Resulting decision

• The injunction prohibiting publication is sustained.