Do away with that hosing off tractor!! Those units are not like a car rhat can sit outside in the weather or go thru a car wash with impunity. You will soon have various electrical probs from rust/corrosion, possibly also various bearing failures. A good blow-off with cmpressed air is much better. If needed, a judicious wipe down with a rag and bucket followed by a quick drying in the sun can work.
Worst of the washing options are the power washers - they will blast water into any number of no-no areas...