cwnut got it. I have been using the bowl covers for about 4 years now. They can be hard to find. Super Walmart usually has them. They fit in your pocket and are nice to have if there is a chance of rain.
I've been known to wrap/tie the control box up in a couple of plastic grocery bags - one facing forward and one facing backwards. Effective and easy and one size fits all.
Don't mean to highjack but I worry about resting my MXT on the ground, especially beach sand. I've thought about making some little legs or something. A towel to set it on makes me have to relocate the target, ideas?