Rear Bumper Problem

[JPJ]

When I was taking off the rear bumper I managed to shear one of the bolts. I managed to remove the stub but along came the captive nut as well.
Anybody got any clever ideas other than welding a new nut onto the bumper as to how I can re-attach as there is no room to get a spanner up behind to hold the nut steady and I don't possess any welding gear?
Is it possible to drill through from the outside face of the bumper and then bolt straight through the cross member that way?

[Tony F]

No reason why you can't drill through the bumper for access, I doubt it would have much effect on the strength of it. I have certainly done it a few times to steel front bumpers on a variety of cars over the years to fit things like spot lights. However to do so to actually mount the bumper (which is what I think you are proposing) I wouldn't like to say.

Would a Rivnut work to replace the captive nut?