Tom this is what I use
A light force handle mounted through the roof of my Defender - This is much better than using anything motor/rotary based, like a rotolight style you have so little control at all, I would not recommend them, if you do not want to mount a handle through the roof a suction mount would do, but theres an extra cable and the chance of it coming loose.
I run the video cable straight through the light force handle, keeps it very neat and no need to have windows open trailing a video lead in from the roof.
I mount the thermal using a pulsar tripod adaptor, there abo