Bri -
I've sprayed automotive type acrylic for years with no problems - even over Tamiya acrylic and enamel primers. Mad, you say? Possibly..........I do this mainly because I make a lot of civilian airliners and cars that all have gloss finishes that I need to polish out - the auto stuff takes canding and polishing very well.
I always allow the primers to dry completely, and I apply several "dust" coats of thinned auto acrylic - if you dust the coats on, the "hot" thinner has a little time to flash off before it hits the surface of the model, preventing the hot paint from attacking the primer.
After several dust coats and adequate drying time (as Quincy says, if you can smell it, it's not dry), a thin wet coat is then applied, allowed to dry, then another wet coat. This usually does the trick.
I've never had a problem with the auto acrylic attacking either the primer coats or the styrene. I guess I've tailored my spraying techniques to avoid the normal damage.