I did a quick crude check, the holes in the hood are very close to 1/4". The OD of the "ridges" on the clips is 5/16". Some of the sites list the diameter of the clips and if they go by the OD of the ridges it would be 5/16 even though the holes in the hood are 1/4". I am wondering if a regular 1/4" OD drywall anchor inserted the hole with a regular screw and fender washer might be the way to go. I think I am going to try and put it back on.
I think that's a very good idea if they fit.
1) Don't use sheet rock screws! They are not intended for outdoor applications and with the slightest corrosion they are likely to break off at the heads (even without corrosion). Use galvanised or coated screws if they will work.
There are other kinds of anchors, expansion anchors etc. if you can find any short enough- not sure how much space is there behind the hole (rainy and wet where my truck is parked in long grass so I don't want to go out and look).
Light (thin) fender washers would work and metal insulation plates designed to anchor wood fiber and perlite insulation might work better but where to get in small quantity? Local roofing contractors that do flat roofs (asphalt) should have open boxes lying around and might take the time to grab what you need. They look like this. The ones with the tiny punched holes around the center have small barbs on the other side intended to hold single ply roofing membranes down under the seams helping to prevent them from slipping and pulling against the seams but you can just flatten those with a light tap from a hammer and they'll function the same. Plastic insulation plates are 3 in dia. a bit too big:
http://www.trufast.com/products/galvalume/
As far as fire under the hood in a diesel? ... your decision on that, although I've thought about carrying a small fire extinguisher to help someone else out.