AutoCAD Inventor :: Small File Size When Exporting

I am trying to export and save numerous Inventor Assembly Models, to send to various customers to import into their models. I have been saving them as .stp files, but they are very large files after exporting, and I'd like to know if there is a way to decrease the exported file size. I could zip them after I create them, but I was hoping there was an easier way or different format than .stp. I could also suppress numerous internal componants, but I would rather not have to go through that task either. In the end, they would really only require the outer shell, with any externally viewed holes still present.