Here’s one of my camping/ emergency/ car work lights.
I have a modded Coleman 4D lantern (Coleman 4D camping lantern mod), but I imagine that would be too big for back packing.
Which ever way you go, the simplest option would be pretty much what I did for that emergency light - 1 LED, a 3.7V battery, an AMC7135 based driver and a USB>li-ion charger board. You can then charge the light from either your car (using a 12V>USB adapter) or from your 18650 USB power supply.
Having used this light a bunch, both for camping and working on the car, I would go for a 1A driver (either a Nanjg105C or Kaidomain V2) with low/med/high. I very rarely use High as it’s very very bright in a tent or next to a car. Med is very useful and Low is handy if you want a reading light after every one else has gone to sleep (or want to make the battery last for days). If I were to use it in a cabin, I’d rather go for more lights than upping the drive current. On the plus side, on Med it should last for >12h 
I’d also go for a neutral white or warm white LED. The cool white in this one is quite harsh indoors and I’m about to swap it out for a neutral white. I’d also use non-acetic acid silicone to secure the battery and charger board as the hot glue I used didn’t stand up to the repeated drops I subjected it to