Torqeedo Battery Bag
This battery bag is actually made for the Travel motor, but it works well with the Ultralight battery. It has enough room for a field repair kit, including a spare prop, hex wrench, spare magnet, can of WD-40 and a few other extras. After filming this, I figured out that the charger also fits inside with these items, making it a nice single grab of everything you need in one package.