wanting to temporary attach a dummy spot light to the A pillar of my car. I have a striped down version with the base but its top heavy and "weather proof gorilla tape" fell off after a rain.

Need a rectangle shape around 3"x1/2"x1/8.

Know of any mini super strength magnets?

rare earth magnets. don't know where to get them, or how much. they are very powerful, be careful, don't let body parts get caught between them and surface. we use them at work

I did order a rare earth magnet but didn’t do the job. Maybe I need a thicker one.? Also thinking about having another magnet underneath the attached one on the housing base.

we do stack them one on atop the other for more strength

Try this company.
https://www.kjmagnetics.com/
They have every magnet that you could possibly think of.

Yes I think I found the size I was looking for.