I started with a
Gomadic AA battery box and two rechargeable Lithium battery packs.
On the third day, I lost the micro-usb connector which allowed the AA box to charge my phone and Di2. So, thereafter, I mainly used the battery box, with a mini-usb connector which I had not lost, for my Garmin, and the battery packs for the other two gadgets. I also bought two more lithium packs that evening so that I had a bit more range. So, having everything fully charged at my last hotel in Bosnia, I was able to get to the finish 3 days later without needing to stay in a hotel again to re-charge.
I got a cardboard box from a local shop. Canakkale is a fairly big place with lots of shops selling bikes (a lot of the electrical shops do BSOs as a sideline) so I think everyone who wanted one got one. I put the bike in there with all my other stuff so I only had one piece of luggage.