I can reply re the dusty/sandy bit..............................
I used a sealed body (LX) with Pentax manual fast glass for many years in the the Middle East, weather sealed lenses had not been invented then.
Nor had rain or wet..........................................
Just be as cautious as you can when exposing you equipment to the elements, remember to give a good cleaning each night with a blower and cloths to remove the residue dust/sand.