This does seem to be way to much work to thwart someone who likes to get FTF prizes. As most have said the easiest solution would be to stop putting FTF prizes in them. I do not even waste time putting a FTF prize in a cache. It is not what is in the cache that is important, but what I am taking you too. Now if someone is going to keep putting caches in my area than they should expect that my name might be the first. Looking at the poster's caches I noticed that they have more finds in less time then mine, and I have some placed in well visited places. If you also feel so bad about someone getting the FTF prize and you still want to have a prize just go back after the FTF and put a prize in the cache. Much easier then worrying about doing some lottery thing, but they are your caches.