It's not too bad, and worth a shot. I'll give it a go and let you know if it works out. Cheers.
Edit: Well I managed to make the stress mark disappear for a second and then it reappeared in a different location as a circular mark. I guess we can call this attempt a failure. The mark is not quite as white, but a lot larger and the edges show traces of heat distortion. I think I got overeager when I noticed the stress mark retreating. I also slightly warped the plastic in a particularly thin area.