Is there a product that will remove approximately 1/8" thick layer of bondo from aluminum? Can't wire wheel or sand it off, will ruin the aluminum underneath.
Paint remover, pine-sol, lacquer thinner, acetone? Thanks for any ideas.

Paint stripper like Kleen Strip AR-343 will soften the filler.It may take a couple applications to completely remove then rinse with high pressure water.

Heat gun.

Lacquer thinner softens 'bondo' so that would be my choice. If you can puddle the thinner, great. If not, spread a paper towel over the mud and keep damp. After a bit, scrape with a plastic spreader so you don't gouge the soft aluminum. I use a small spray bottle with thinner, very handy. Heat might warp the aluminum.

Agree paint stripper will soften it. Aircraft stripper is my choice though I am sure others will work. Apply a heavy coat and cover with plastic to keep it wet. After a few hours, scrape off what you can and repeat if needed.

If there's a layer of bondo on the aluminum part chances are it's been sanded for adhesion already so carefully sanding it off won't do any harm...