I have resorted to this; I removed the fluid head of my tripod, is about 10cm high and very strong
I have circled wire around the fluid head, and used almost struts to secure it. The struts are attached to the wire ring around the fluid head and then connected (melted into

) to suction cups which i will attach to the dashboard using super heavy duty tape. I will also tape the fluid to the dashboard as a safety precaution!
Overall, quite a successful day, did some functionality testing, doesn't come off and vibrates only slightly!
FS