So here is my thinking on the skids and sand questions.
I believe it would be easier to get unstuck in the sand with full skids due to their position at the frame and distributing the weight of the vehicle across a wider, flat surface when the wheels are dug in...so I believe in skids on.
Without skids in sand the frame rails and cross-rails, would grab more sand and get you stuck further in the softer sand, maybe?
As for having them to avoid getting sand in sensitive areas like rotating shafts etc....the skids don't completely cover things like the front CV shafts, nor do they cover the front steering linkage and not at all for the center, rear, drive shaft so all of that is exposed. I would expect the related boots and universal joint seals to be adequate protection there from getting unwanted things mixed in with the grease. As long as those parts are properly maintained of-course.
It sounds like you drive frequently in sand to the point that removing the skids for cleanup would be extremely tedious. Maybe using a strong, leaf-blower to get the sand out from under the vehicle would be the easier clean-up routine rather than removing the skids? Presuming the sand is dry of-course. Add a 10 month or some other long interval for a full skid removal and cleaning.
Those are just my thoughts as fan of keeping the skids on but understanding that there is additional maintenance associated with driving outside of paved roads.