Yes I do.
https://www.amazon.com/XTPower-MP-10000-External-10000mAh-included/dp/B00935L44E
That plus the adapter works just fine. Turns out the one you posted is the one I bought. Hahaha.
I think had to use some other adapter to connect the two, but I have gotten it to work.
I think something like this would work since it has a 12v dc output port and would charge the mighty. I don't know that other USB battery packs output the 12v that the Mighty requires to charge.
The dimensions look like its slighty smaller than the Mighty itself.
Try these: (search amazon for 12V 3A DC or 12V 3A external battery)
high price:
http://www.amazon.com/Anker-Universal-20000mAh-Multi-Voltage-External/dp/B00B45EOYS
better price:
http://www.amazon.com/XTPower-MP-10000-External-10000mAh-included/dp/B00935L44E
car charger / adapter, cheaper than original):
http://www.amazon.com/Dophee-Portable-Charger-ASUS-1000/dp/B014GSWBJY
good luck :D