I'm thinking this way: when you fasten the screw, chances are there will already be a considerable load on them (you know, if you give them that half a turn too much)...

I want to know for sure, so I am just going to test them. Make some sort of setup so I can put weight on one...and see what they can hold. Maybe if I can find a heavy fishing scale (dynamometer in dutch, don't know the english term) I can work with a steel screw to put tension on them so all that dead weight has no chance of crushing my toes...

I think we all under estimate the strength of these bolts, but I won't take chances on loosing a plane on something stupid like that...