Also a good idea of course! I generally just take my cellphone and leave it in an airplane mode, but I do like to record GPS tracks of the hike, use it as a map (supplemented by paper maps), and mark nice campsites, interesting waterfalls, etc, in case I return and want to find them again. Since it also functions as my camera, if I'm doing more than an overnight I have started bringing a light external battery as well.

It's a good point though, if you find yourself taking multiple gadgets that need to be recharged with a heavy external battery, it might be worth considering which ones are necessary. Could the phone take the place of whatever functionality the tablet is giving you? Maybe a slim paperback instead of kindle/tablet + extra battery? It all depends on how many things you are willing to carry/tinker with. If it's worth it to you, then by all means, HYOH.