Ok, J.V.
Here's my little trick.
On the underside of the airdam where it will meet the headlight buckets there are two small flat areas for your fasteners.
Get some cardboard from the back of a pad of paper and make two patterns that fit in those spots.
Transfer these to some aluminum flat stock, (I used 1/8")and cut them out.
You may have do some shaping of the mating surfaces so that they fit into the corner of the airdam tightly.
Then using the high strength marine grade epoxy that you already bought at the local autozone, glue them in place.
After the epoxy has cured (a day or so), clamp your airdam in place and mark your hole locations from the top, through the hloes in the headlight buckets with a short pencil.
Drill holes and bolt in place.
Mine looks like this.
Many people have made supports or pans for the bottom of the car that support the airdam on the bottom also.
I haven't done this to mine yet, but may in the future.
Your type III dam's design makes it easy to add a splitter/support to the bottom.
Like "Redbird", A very nice execution of this idea.
Hope this helps.
Mike.