I did majority of my trunk, which is the entire trunk in 1 layer with a mix of FatMat and Secondskin Damplifier and I used an entire 40sqft of that and ran out and maybe 25sq ft of the fatmat, maybe 30. This is the floor, the rear deck under the trunk,flloor, back deck by the bumper, wheel wells and anything else you can think of, lol!
So 80sqft should be plenty for your whole trunk........including lid, lol! Don't know why he keeps saying lid.
Raammat is good, Second skin is also good. Hell I even like my fatMat, which works fine in my install and is a lot cheaper.