bbaker, good luck with your treatment. You are 2000 miles from having to change your filter and 1200 miles from home. I'm sure there is a little wiggle room in there. I changed my filters at 15,700 miles recently. The front filter is still very clean at 700 over. I'm sure you could probably replace the front filter every 30K miles... but its cheap and relatively easy to replace so its not worth the risk. Bottom line, you'll be fine to drive home and change... even if you are slightly over the 15K mile mark.
Again, best of luck, hope you get the treatment you need and a full recovery.