X2 on the wireless magnetic lights with a slight modification.
I stand the lights inside the car on the shelf between the rear window and the back seat (you know, where you used to lay down to look out the back window when you were a kid)
A small piece of self adhesive velcro on the bottom of each light keeps them standing and in place. They are out of the weather, secure inside the vehicle and no danger of one falling off on a big bump.
The wireless lights are about the same cost as a diode kit with the advantage that you don't have to hack into your new car wiring.