I think you are right in trying to keep your electronics protected at all times. My handlebar bag does such a good job of keeping water out that I usually don’t worry about any sort of damage unless it is absolutely dumping. I think this is the reason I don’t take such extra precautions against rain. But I agree with you in that you should try and keep your gear protected at all times. In my case, I feel that my handlebar bag does a pretty good job of that, so I’m not worried about such things most of the time.

Since I get my maps from different sources they are often too large for the Lone Peak map case, so I made this modification: Sew on two D rings to the front of the bag using some nylon strapping material. I use these D rings to attach a larger size map case with Velcro that comes with the map case. It just sits on top of the bag. When I want access to my bag I just flip the map case over. It has worked great.

The second thing I’ve done is added a piece of chloroplast board to the bottom of the bag to make it stiffer. This is the board that political signs are made from. You can usually find one lying along the road. It really helps to support the bottom.