I may have missed it, but your ELT will have a (2-cond?) cable to both an audio alert device (I mounted mine behind my head where I might be able to hear it), and a panel-mounted switch/light panel. Both of those need to be accessible because they contain batteries. The buttons/light on the panel are so you can test the unit every three months, and also activate it in case of impending doom.
Again, I may have missed it, but you'll definitely want some USB outlets for battery-powered "stuff".
You'll also want some way of charging your batteries if you're not going to be flying for a while. I have a Cigarette lighter plug for that purpose wired directly to the battery through a 20A 3AG fuse.
(2018 dues paid)