I have flat towed the Bronco behind an E150 once, just dropped the driveshaft and went about 120 miles. No problem.
recently I got a lot more involved in how all the parts work. As for stuff lubing as you drive, the axles will be fine.
Manual trans- is lubed by the input shaft spinning the countershaft and throwing oil everywhere inside the transmission. With the engine off that oil sits in the bottom. So sticking it in nuetral will spin the output shaft, not connected to any of the gears and not toss any oil around. For a short time, no problem, still has an oil film on it. Long time you may have issues. Stick the transmission in top gear just to keep it from spinning.
Auto trans - Similer to the manual. Engine needs to run to spread the lub around. Just the oil is a little thinner.
transfer case - Again the lube is tossed around by the input shaft spinning the counter gear. Just kicking the transfer case in nuetral stopps the flow of oil. Just running on the oil film. Good part is the output shaft is on bearings instead of bushings. I feel more comfortable with marginal lube on roller bearings then on bushings. (If you want to reasearch that a little more look up marginal lubrication on plain bearing turbos vs. ball bearing turbos). The transfer case has a neat trick. By LOCKING in the front hubs, it spins the front output shaft. That happens to be submerged in oil. That flings oil all over the inside of the case, Almost the same as the engine running.
So if you want to be as save as possible without removing a driveshaft, leave the transmission in top gear or park to prevent damage there. Put the transfer case in nuetral. Lock in the front hubs. This is the highest possible drag behind you, but keeps everything lubed. I can't do this because I don't like to spin my front driveshaft that fast with the steep U-joint angle.
Other option is to just drop the rear shaft. You can still drive it around in a pinch by locking in the front hubs and putting it in 4WD.
The Explorer will be at it's limits. Watch the brakes, you will be stopping for 2 instead of 1. That is where I like trailer brakes. Downshift a lot when stopping. Engine braking is your friend.