Has your bonnet already got locating pins in each corner ?
Those properly done should hold the corners of the bonnet quite
securely.
The default Quantum ones are rectangler furniture block on the body and
matching holes in the flange of the bonnet.
Unfortunately it’s quite hard to work out exactly where the hole should be
so they are quite often oversize.
I didn’t use the plastic blocks, i fitted stainless pins into the body
(about 1/2” dia”") with a taper on the end, and a large grommet into a hole in
the bonnet.
A self adhesive rubber seal around the rear of the bonnet will also help
reduce the movement of the rear of the bonnet but if you’ve not got vents in the
bonnet it might increase the temperature under the bonnet.
Anyway, back to your original question, there is nothing inside that area
except a void and the big steel box section where it kicks up from the
sill.
If you drill too close to the edge you may come through under the wheel
arch.
If you have the tools drill and tap the fibreglass rather than using self
tapping screws.
If you have to use self tappers then countersink the hole so that the gel
coat is clear from around the edge, without that the screw will almost certainly
crack away part of the gelcoat around the hole.
Jim