I would gues that if you loose the front bumber upper plastic fasteners you are able to get it that much open that you are able to put 3mm thick abs plastic sheet behind the upper grill. I have done that to many cars and it can be done. Just be careful with the radiator not to make holes in it while installing.
Usually there is some rubber there in newer cars but that can be bended away so you can slide the block in place.
On the lower block you can put it over the bumber so its easy to remove.