This one is well reviewed, I think currently it might be the only external battery pack with QC2.0 http://www.amazon.com/Aukey-10000mAh-Portable-External-Supported/dp/B00UBDI7EC/ref=sr_1_9?ie=UTF8&qid=1435951008&sr=8-9&keywords=quickcharge+2.0
I bought this a year ago (still going strong) and it supports the turbo 1 aka OG turbo via QC 2.0. charges the phone all the way in 1.5 hours and i can get two full charges from the battery pack. It does not support the QC 3.0 standard in the turbo 2 but for $18 and free ship with amazon prime i can recommend it.
This is probably way too big for a thru-hiker. I used a 4600 mAh pack last year and it was plenty. Also, the pack doesn't mention any sort of quickcharging technology for the input.
I bought some Aukey 10400 QuickCharge 2.0 packs for $20 each for my bikepacking. I wouldn't go over 10k mAh because it takes too long to fill back up. The Aukey packs support Quickcharge on the input and output. http://www.amazon.com/10400mAh-Portable-External-Qualcomm-Technology/dp/B00UBDI7EC/
I haven't had the chance to do trail testing on this yet, but I'm excited about this battery pack: http://www.amazon.com/Aukey-10400mAh-Portable-External-Technology/dp/B00UBDI7EC/ref=sr_1_1?ie=UTF8&qid=1456828001&sr=8-1
It uses Quickcharge 2.0 for both input and output. That's faster than a standard USB charger and means more charging gets done when you're sitting in a restaurant or whatever. You'd want to get a Quickcharge charger too. I got a dual one to charge my phone and battery pack at the same time.
Check to see if your phone can take advantage of the Quickcharge capabilities.
This is what I could find: Aukey http://www.amazon.com/Aukey-10000mAh-Portable-External-Supported/dp/B00UBDI7EC APE MP5200Q (availability: unknown) http://www.ape-battery.com/ljz/EnProductShow.asp?ID=221 Incipio http://www.incipio.com/ces-power/quick-charge-portable-backup-battery-6000-mah.html# I had been announced back in January at CES but I haven't seen it selling anywhere yet.
I do have an update: Quick Charge 2.0 - power banks, wall chargers and car adapters
I would suggest this battery pack too. http://www.amazon.com/gp/product/B00UBDI7EC?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00