Well, creative is coming up with your own solution. Once that's been done for you, it's just adoption of the creative solution. Here's what I did on a Trek road bike with tight clearances and no chainstay bridge:
Start with a Planet bike Blinky seatpost mount (or any similar lighting mount-- if you don't have any, see if your LBS has any laying around in a parts bin). File off the unnecessary bits, and use a piece of inner tube as a shim if necessary, to attach the seat post clamp piece to the chainstay:
Drill a hole in the part that the light normally slides into (in the above picture the hole hasn't been drilled yet). Use the hole to bolt the square light bracket to the fender. Since this part usually can pivot around the seat post clamp, that allows it to butt up to the fender at the perfect angle, since the chainstay and fender attachment point are not at a right angle to each other.
Here's how it looks from the drive side:
Another closeup:
Barely noticeable "in the wild":
I've ridden several hundred miles with this setup and it hasn't come loose, rattled, or gone out of adjustment.