Questions about running generator in back of truck

We have a box that sits over it when not in use to keep it dry but we have to remove the box to run it.

We try not to run it out in the rain.

It shouldn't be too hard to string up a small tarp if you will use it a lot in the rain. If it's a couple feet above the bed rails, it should leave plenty of air to cool it while keeping most moderate rains off it.