That OEM spoiler is totally lame and I got rid of it on our 2006 TSX 13 or so years ago.
I was lucky and found a color matched non-spoiler truck lid locally. It wasn't cheap but I was able to sell the old truck lid and spoiler to recoup some of the cost.
The rear truck lids are identical from 2004-08.
It is going to be nearly impossible to find a color matched trunk lid in good shape for such an old car.
Your best best is likely to get a body shop to weld up the holes on your trunk lid and re-paint it.
Plus when you remove the spoiler, you will need to swap in regular trunk lid torsion springs.
That spoiler is super heavy.
The 3rd brake light harness will plug directly into the 3rd brake light on the rear window panel.
Plus leave off the Acura and TSX badges. There are no locating holes for those.