If you haven't already, you should go to the Solo Wargamer's Assn website. I know they've had a number of WWII solo rules for naval warfare printed in their magazine, Lone Warrior. Tremendous resource for solo gaming. The blog is at:
lonewarriorswa.com
I edited and published a booklet, Solo Secrets of Wargame Design, Volume 3 in the Secrets of Wargame Design: A Tabletop Toolkit of Ideas, Analysis, and Rule Mechanics series based on Wally Simon's articles. I released Volume 7: WWII Secrets of Wargame Design earlier this year -- the May issue of Miniatures Wargames reviewed it. Volumes are $19 USD each from onmilitarymatters.com (US) and whatever the UK pound rate is from caliverbooks.com (UK).
Contents of Solo Secrets:
•Simple Solo Guidelines: Morale, Data Sheets, and a Napoleonic River Line Attack
•Good Morning Vietnam: Cards, Squares, and Sequences
•WWII Efficiency: Too Much Damage, Loss Points, Reaction Points, and Combat Points
•Napoleonic Equality of Inequality: Simon's Theory of Fire Power
•Scenario Generation: A Line in the Terrain
•Speedy Solo Siege: Zones, Building Points, and the Passage of Time
•Third Time's Charm: Modern Solo Squad Skirmish
•Renaissance Squared: Grids, Groups, and Grinds
•Bad Blood in the Balkans: WWII Command, Control, Activation, and Quality
•Rules are Greener: American Revolution Response Chart and Efficiency Levels
•Solo Hastings: Flights of Fancy?
•NATO Rescue in Serbia: Pop-Up Squads, Prisoners, and Running Battles
•BONUS: The Wally Quadfecta: Universal Guidelines for Good Game Design
All the articles highlight the nuts and bolts of rules mechanics to help you (in Wally's words) "produce a game which keeps all players continually busy and interested in what's going on."