I think that there is plenty that you can do in this time frame. Shadowing is a great idea and really doesn't require much time. I was able to shadow during some 24- and 36-hour shifts and got a ton of exposure quickly.
Also, you can consider starting something now that will turn into a longer activity. Maybe consider a mentoring program. They usually require one year of service, but no problem with starting it now.
That is, there is plenty to do if you need clinical/volunteer ECs. If you need research or leadership or anything that shows any real continued interest, you've put yourself in a pretty impossible position.