Fording does not need waterproofing, else it's not much of a ford anyway. In the Army, I hated the swimming exercises for the tracked vehicles. The pre-swim and post swim maintenance was a hassle. Plus way controlled environments, no fun at all. The Army will go to great lengths to NOT deep ford. Most track vehicles can swim, but it's gotta be for in a pinch. Call the engineers... for a pontoon bridge! Anything not fordable, and deep, using a vehicle that cannot swim becomes a submarine... or an anchor!
Look for a good ford and you won't need a snorkel.