You dont need to do EVERY square inch like that... Just knock on the panels and whichever pars sound hollow, add deadener. If it ssounds solid it wont be an issue.

Flat surfaces resonate the most... In trunk cars I've even plated weak spots with metal strapping/nuts and bolts on the rear parcel shelf before deadening

I've been looking for this stuff in Canada for a while. I finally found a comparable product at Rona MULTIPURPOSE ALUMINUM WATERPROOFING MEMBRANE by Resisto.ca ... It's only 40 mil thick, but it works well. I was worried about the possible of a smell from the tar base, so I went around the edges with aluminum foil duct tape, to seal in the smell. So far so good. Seems to work as well as Dynamat but costs way less, and by sealing the edges with aluminum duct tape, doesn't have a chance of smelling.

I used it in the studio to deaden a very resonant table.

https://www.caraudioforumz.com/attac...ine=1360269977

I also filled the legs with silica ( aka fancy cat litter ) to deaden them too.