Review on Macally Apple Watch Charger Stand: The Perfect Charging Station for iWatch Series 6/5/4/3/2/1 - Black (44mm, 42mm, 40mm, 38mm) by Mark Meyer

This is one of the smartest watch charging ideas I've seen. It uses the charger that came with your watch. Installing the charger to the charging station is a breeze - installation takes less than 5 minutes. The only thing I see that might be problematic is that the charger itself has such a short cord that you may need to plug in some sort of extension cord to place the charger/cradle in a safe but convenient location. It should easily fit in your luggage.