Water and electricity are not a good mix.
Dew is distilled water, but it can pick up any sundry of dust, dirt, or other contaminants. That's what gets bad.
My telescope has a nice long dew shield on it. So rarely do I see a dew problem.
I also have a tote (Plastic container) I set on it's side, then set my Laptop in it so it stays covered from dew, but easily accessible.
I can also drape a towel over the container, but usually my computer and mouse are safe enough.
If anything is wet when I come in for the night, I just let it set out to warm and dry on it's own.
Since I live on the edge of the desert anyway, my climate is pretty dry, generally.
If you want something fancier (I don't.) there is a Laptop Dome. Which is a cute and practical pop-up tent for your laptop.
Or simply a cardboard box on it's side.