As to your assertion that people steal code all the time, I can't speak to that, as I don't know all people or all code well enough to judge. Your original question was technical in nature rather than philosophical, and I'm very sorry I can't give you more assistance (I have never had an occasion to compile my code in order to protect it).

It seems to me that since your only practical choice is to compile the code, that you probably ought to go back to the source, namely - ActiveState and/or C. I'm fairly sure that there is no magic-bullet answer to be found from the Perl side of things.

Best of luck to you!