If I'm not mistaken, none of them have a charger designed to run the light while charging. The design of virtually all of them would make that awkward to say the least. Example, the charger for the Mag covers the head of the light and blocks the beam. The US charger is a 2"x2"x3" block that snaps around just underneath the head and makes access to the switch a little awkward... Not sure about the TL but believe it is similar to the US.
Meanwhile... all of them are NiCad which does not handle heat or cold all that well. If you anticipate extreme heat or cold you would need to mount the light in a somewhat protected position, say under the seat to prevent the NiCad cells from cooking in direct sun or freezing.
Also, you need to consider charge speed. If the light is to be used on a constant basis, the you may need a speed charger - availability of which may affect your decision. I.e. - if you anticipate draining the light during a typical day, a speed charger may be a necessity. That or a piggyback or spare cell pack.
As said previously by Paulr, if anticipate spotlight type usage, a spotlight may be your best choice. I have a leo friend that carries a baby spot in the car - very small, only a little larger in diameter from the US. About 1/4 mil CP.