Just stumbled across this method of data expansion for iPhones using a lightning cable.
Product details
Designed to be the perfect companion for your iPhone, the iXpand Flash Drive offers an easy way to free up space on your iPhone, automatically backs up your camera roll. The drive has both a flexible Lightning connector that works with most cases and a USB 3.0 connector to plug into your Mac computer or PC so you can easily move your stuff where you want it. The iXpand Flash Drive also includes encryption software that lets you password-protect files. Take all the photos and videos you want - the iXpand Flash Drive delivers a fast and simple way to free up space on your iPhone so that you’re always ready to capture more memories.
Product Features:
Automatic photo backup
Works with most cases
USB 3.0 High-speed transfers
Compatible for iPhones, iPads and computers
16GB storage
Good find. Also available for a fraction more ($33.11) but with free shipping via Memoski on Amazon Prime (plus 7% CR/SB) if you can't get to a store and need to have it delivered.