Just thinking about a deep water crossing and not drowning the motor out...
How do electric fans like to be submerged?
Air intake ideas?
Sealing up engine, tranny, axle vents, etc?
Sealing them isn't possible - their seals can't be that tight (because they'd wear out instantly), so they can't hold any pressure. That means they have to "breathe" somehow, for altitude & temperature changes. High breather tubes will allow them to vent in those situations, but also when submerged and the water leaks in past the wheel/crank/input/output seals. What about the PCV system? Even a mechanical (gas) fuel pump has a breather hole that you have to address somehow.
And that's not the only issue. In addition to the spinning fan (which can be partially solved with e-fans, but as you noted, THEY also aren't sealed for submerging), spinning alternator (& its soft carbon brushes), vented PS reservoir at the cap, and all the electrical components that don't work well after being soaked with muddy/salty water. Even without a fan spinning near it, the radiator, block, & all the coolant will also chill & contract, meaning that the coolant system will suck in whatever's around its overflow/vent.
Then you have to think about what's going to happen to the exhaust manifolds (gas OR diesel) when they go from ~1,000°F to whatever the local water temperature is, in a second or 3. And the cylinder heads. And any incandescent light bulbs that are on.
Now, you're just left with all the little insignificant things: fuel tank, HVAC, upholstery, seat belts/buckles/reels, door/tailgate/hood latches & hinges, chassis/underbody rust...
All of those (& many others) are why only a FEW expensive (military & modern sport) vehicles are rated to go from land to water
above the wheel hubs.
If you want to play in the water, bring a pair of boots, or tow a boat behind your Bronco. ;D
Otherwise, just plan on rebuilding the hubs, draining the axles, and repairing/replacing other things any time you go deep.
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)