It's been raining a lot recently, so I've been cooped up indoors. But I've worked out that if I go caching in London, it'll be mostly on tarmac, so I shouldn't get too muddy. So I've been looking at puzzles there.
I also tested the bike with the boosted voltage, and yes, I do get more torque. That's a nice thought!
I tried out the Deans connectors; it takes too much pull to separate them. But the XT60s look more likely; I've started doing some wiring using those, and they connect and separate without too much force. What I might do, is use them for all connectors except for the final connection to the bike, which I'll leave as a kettle, because I do need it to be pretty easy to disconnect the batteries, so that I can remove them from the bike before lifting it over an obstacle.
I also bought another battery charger. I already had two; my idea was to use one for fully discharged batteries, and the other for partials. But I'm getting through 4 and a bit batteries per day, So in future, I'll out two on each charger, and the partially used one of a third. I'd be nervous about putting a partially dischaged battery in parallel with a fully discharged one, because the voltage difference would drive a huge current through the wires.