AeroModder -
Yeah, thanks for making the effort. They are pretty cheesy.
COcyclist posted what I was suspecting. The triangular base you see in all the pictures is generic and attaches to a *custom* base designed for your car. This gives the base a 3-sided "stepped pyramid" look :
Therefore, if you make your own smooth looking base, you can attach the mirror to that. If the Tempo had OEM side mirror covers in a super-no-frills model, that could be your base.
Again, notice in the above picture that the triangular base is not "flush" to the one that attaches to your car. Ideally I think that you would want to inset the base.
CarloSW2