Stay out of the water? No seriously, I have a peugot 307 air filter mounted on the aircon mounts and some motorsport grade trunking taking the air to the turbo. I then have silicon and alloy taking it to the intercooler and back to the manifold. Its a lot of joints and I wade carefully, but so far it's been OK. I have had water over the bonnet when crossing a river in Northumberland last summer and that's without a snorkel, risky but fun. I reckon the seal on my hoses are as good as they are on a standard Land Rover instalation, it's just that there are more of them that could go wrong.
Graham