Stowing Secret Stuff
1. Get a Samsonite briefcase (the thinner, 3-inch model) with a COMBINATION lock. This should look a bit travel-worn/ugly and can be bought at pawn shops for $20-25. The combo lock opens fairly fast for emergency access.
2. Affix some type of religious organization/logo on the case's outside, along with a minister's I.D. tag. Also, have "Content: St. James Bibles" stenciled on the cases. (If you find this sacreligious, use your imagination for something else... like, umm, "St. Hillary's Home For Unwed Mothers", "San Francisco Labs Terminal HIV Specimens", or "PMS Sanitary-Napkin Recycling, Inc.", etc.)
3. Note: If some overly-intrusive gendarme (lacking Probable Cause) searches your vehicle -- and asks you to open the case -- you can tell him you can't/don't know the combo because it belongs to (a) your Sunday School teacher, or (b) your congressman/uncle, Barney Frank.
4.. Use a common bicycle security chain (thin steel wire) and lock to secure the case to the front seat rails... on the floor BEHIND the front seats.
5. Cover the case with a big clear plastic bag filled with "soiled" underwear (actually, besmirched with chocolate and raw-liver-blood stains).
6. To deter prying eyes, have your SUV's windows tinted dark, but avoid the all-black/Darth-Vader inner-city pimp-mobile extremes.
7. Buy an SUV with a DARK colored interior (to minimize light reflection). This also "helps" the window-tint obscure the vehicle's interior contents better. If you already have an SUV with a light-colored interior, consider having the seats re-covered and new dark carpets/mats installed.
8. Have discrete "St. Boxstein's Youth Foundation" or "For The Children" signs magnetically affixed to your vehicle's passenger doors. (You probably ought to remove these before you pull up to some Nevada whorehouse.)
9. Remove any "NRA", "Vote Republican", "Violence-Prone Veterans Against Photo-Op Goose Hunters From Massachussetts" stickers, or dead give-away vanity plates. Replace those stickers with innocuous "Baby On-Board" or "We Brake For Vegan Tooth Fairies" bumper stickers to "sell" your SUV's "soft" (the last place you'd ever find any, ahem, evil guns) image.
10. Ditch the 20-inch chrome wheels, the Texas Longhorn hood ornament, and the chromed safari-cowcatcher. To paraphrase what Dan Akroyd said in "Blues Brothers": "You're on a mission from God!"
Beyond all this, consider having concealable "secret" storage compartments custom-installed inside your SUV's front doors. If you live in a small town (where secrets last 10 minutes) go to another city to have this work done. Don't show it off just to get laid or prove how cool you are, and don't do this if you regularly visit inner-city chemical-recreation zones, cat-houses behind in their taxes, high-security federal buildings, or Mexico.
No, I don't play a pimp, dealer, or secret-agent on TV.