On another thread I mentioned that I was also concerned about contamination on our two SP bikes.  I reduced the exposure by putting a small square piece of duct tape over the key frame opening, then slicing an opening fore and aft with a utility knife.  With the key in and turned on, much less exposure to the key mechanism from outside crud.
I've also found I can leave the key in and "on" 24/7 without any concern for battery drain as long as the display is turned off.  And if you use other security measures the bike is safe.