Like I said... this may be overkill for your purposes but this is what I did...

Here is the disassembled flatline. The second hole on the left is where the bolt goes through into the shroud. You can also see how I notched out the bottom of the plastic quick mount. Isn't beautiful but it is solid:

Here the rail is screwed into the shroud and you can see how flush the quick mount sits:

Now... on the opposite site I drilled another hole to get the nut-driver through because I couldn't get needle-nose or anything else in there to hold the nut. For me... this isn't a big deal as the battleshroud rails cover this hole (see next photo - opposite the nut):

From the inside - you can see the nut (and washer) that hold the quick mount in place:

This is on the marker:

I hope this helps... let me know if you have any questions.

WinterKill