Dynamo hubs

This depends on what you're doing/how much nightriding your doing/how often you want to post cool photos on the internet and watch cat gifs but my thinking is...

Joystick (essentially glorified battery with a big LED on the front) can charge from the Sinewave/Kemo/Plug etc. but NOT directly from the dynamo. Do this during the day.

Use the Joystick a bit a night.

Joystick turned off and then used to charge iPhone/Garmin while sleeping (cable available from Exposure or you can whip something up with a soldering iron). Plug the Joystick back in to charge when you set off after breakfast...

If you want to charge Garmin or iPhone on the go, you can use the Sinewave/Kemo etc. but if you go slow (mountain biking yay!) the output switches off and your phone will buzz and light up or your Garmin will beep to say it's unplugged. This might not be a problem, but can be a bit annoying. If you want to make things slick and painless, then running a small cache battery will keep the devices charging until you pick up speed again. If you have the Plug there is a cache battery you can stuff up your steerer tube, so you don't have to worry about the on/offness but I think it's a fair bit more £££

Obviously this doesn't work so well if you need to ride during the night and need the Joystick blasting fullpower all the time then sleep during the day to avoid the heat or something...