Avoiding salted sleet

So I have a '06 with an almost rust-free frame. We anticipate snow within the next couple of days and of course of the city will go nuts with the salt on the roads (most of the time we don't need it). I will have to drive down some salted roads, and anticipate getting some salty sleet underneath the truck. If I just hose down the underside of the truck, is that enough preventative measures to ensure longevity of my frame? What areas should I focus on? My mechanic mentioned the welded bits are what to keep an eye out for. Thoughts?