You could modify the Travel Hub, include a converter from 5V to 12V and solder it to the charging cables. But I don't know whether this influences the iLiads USB capabilities. Maybe it even fries your USB chip if some voltage fluctuation occurs. This setup would also be very lossy as you have to convert from 5 to 12V and internal from 12 to 3.7V again.
Hmm, the Travel hub needs 9-12V input voltage. Why not take a 9V battery, construct some kind of adapter and attach it to the hub? This would make a nice emergency power source. Would the battery give enough energy to charge the device completely?