My Nano and Black Berry has survived 4 years of charging year round in the FJR and the Nano you can a couple years more in my KTM's glove box. Now, I don't put it in there if I'm in traffic and its 100 plus out. A black tank bag with power for charging gets very hot too in direct sun. My Ipod gets hot enough that you wouldn't want to hold it for very long when I forget its in there. Its 6 years old, still working. Been across a few deserts. I try to charge stuff in the morning when its cooler out if its in the glove box or the tank bag.
Its easy to add a Powerlet, the battery is up front and easy to get to. I use a single SAE battery lead. Powerlet makes adapters that work with the SAE connector. So, one lead coming from the battery for my Battery Tender, tire air pump or charging phones and such. I usually just use the glove box for the phone and Ipod unless I want to charge a phone with the key off but, then I'm always thinking I'll forget it and kill the battery.... So I tend to charge things in the morning when the temps are below 100 and I'm good to go by lunch with my Ipod and Phone all charged up. In the winter the temps are no concern to me and I charge things in the little box as needed.