Agreed wholeheartedly!
If you don't put rivets there vibrations from the engine running might eventually break up the bondo/paint and moisture and gunk from the engine will get in there and corrosion will start. Rivet 'em up fer sure!
BTW, Flash has a few spots on her like that

.
At least you didn't drill into your hand yet (which I've done

).
Off to the airport and best,