craig, sorry not a plumbing repsonse but I have seen some of those kids safety items from one of the big box stores that was pretty much a glorified kid proof clamp for the toilet seat to help just what you are talking about. i had a friend whose child loved to flush a plethora of objects (including a small remote for his stereo) and he got that and solved his problems. The issue of course is then you have to put up with taking the clamp off before you go and you have to do the same for your child. As long as he/she is good at telling you when they have to go it is not a problem. After his remote got flushed my friend figured it was worth the annoyance.