That's what I was thinking.... That or maybe try and get some cheese wire behind the plastic and pull it alternatively and see if it melts/wears the plastic down enough to just pull gently and break
Going to have to stop using this bloody swype keyboard.
The clips although structural so to speak don't really have any strength. There are two tabs that hold them onto the wing with a bolt and the bumper has a number of small lugs that fit into gaps in the clips. They are a sacrificial part so are designed to fail. Your bumper won't fall of though, the centre bolts top and bottom will make sure of that, it would just flap a bit at the sides.
It really would be interesting to see if these could be printed.
They are not under too much tension either, as Srhutch says, most of the carrying is done by the centre of the bumper. It'd be great if these would be made cheaply...