dude, if someone you know has a stroke in the backcountry, they're probably F'ed anyway, aspirin or not. Focus on something productive, like gashes and broken bones. Kids having a stroke while hiking (the topic of this thread), or randomly passing someone else in the backcountry having a stroke, seem like they might not really be the statistical probabilities you should optimize for.
For kids, I add the following stuff to my regular "gauze and bandages" kit -- bandaids (kids just seem to like them), blister-pads (worth every penny), extra duct-tape, itch creme, extra sunblock and children's Tylenol/advil/etc. and, last but not least, TWEEZERS. My kids attract splinters like magnets to a fridge.