This is all true..... I have been, just today down here in Houston area, been in some deep water on the roads themselves.(2 to 3 feet believe it or not).
I got to test out my new snorkel....I assume it works because i made it through fine.....EXCEPT my clamped together muffler and cat came off.Now i assume it was due to the water pressing on the front of the muffler and pushing it towards the rear of the xj. Once i got out of the water, i bolted her back up but i realized the exhaust is a much overlooked part of water crossings.
That thing needs to be water tight and very secure.AKA Welded, not clamped like mine. It also needs to rise up the side and above the predicted water line if you expect to go anywhere above the bumper really.Once you let off the throttle in water .....the water wants in the exhaust and,....well then the exhaust cant get out,...and you have pressures where pressures werent and Mr 4.0 shuts off.
I too spent 5 years in the Corps (ERRRRR KiLL)...and i have a lot of memories driving and havin a blast in humvees out on the tank trails. Thats probably what made me get into Jeeps,..or insanity and a sense of self abuse.
But i digress.Its pretty tough to totally seal an electrical system other than keeping them coated (PMs!!) Unless you wanna develop something and then get a patent, and sell it!!
Neccessity is the mother of invention my friend.
BTW i love being confident in the water. All these chumps in thier honda (look how practical i am) vehicles on the side of the road camped out in thier stuffy car whilst i cruise by... HAHAHAHAH!!!!!!!!!!!!!!! punks
Either way the best way (and sometimes most expensive) is to try it out and find out the weak points....Good luck adn post a write up when you discover something helpful