Hatch skinning wood and aluminum?

I had planned on skinning my hatch with 1/8" baltic birch and .042" aluminum, but in speaking with the Teardrop fix it shop yesterday I was told that there is no need for the birch under the aluminum. The weight is the main objection apparently.
I skinned the body with just the aluminum, no under layer, and it came out fine.
Any thoughts on using just the "tin" on the outer hatch surface? I'll still use birch as the interior liner if I do it that way.

I skinned the body with just the aluminum, no under layer, and it came out fine.
Any thoughts on using just the "tin" on the outer hatch surface? I'll still use birch as the interior liner if I do it that way.
