The worst thing you can do to a truck that is driven in slush and salted roads is to put it into a heated garage at night. The ice and salt build up beneath will start to melt and run into places you don't want it to. If it stays out in the cold or in an unheated garage this won't happen. By all means do wash underneath it whenever you can.
I also have had a collector truck and could not really enjoy it for fear of damage or even silly things like being caught in a rain storm. It was no fun so regrettably I sold it. My 49 is a driver and although it is not abused I can sleep nights without worrying about it.
Bill