I have switched over to Second Skin Audio products for our sound deadening. Excellent product. I have been using their product called Damplifier Pro for our base layer(after rust mitigation of course). On some cars we coat the entire floor, roof, inner door or whatever with the Damplifier.....no metal exposed. On my Troopy we even went so far as to seal the gaps of where the sheets of the Damplifier(which is their variant of a butyl/aluminum stick on sound deadener) with foil tape....zero gaps.
When we get the Damplifier installed to our liking, we top coat with 1-2mm of their product called Spectrum. Spectrum is an all-in-one thermal and sound deadener liquid.....spray it, brush it, roll it, trowel it.....very easy to work with. Water cleanup. Spectrum can be used as undercoating and can have a thickening agent added to it so it will not drip or run....it can be applied with a putty knife...it's that thick. They call that Spectrum Sludge.
My floors in the LV were exposed....so nothing on them other than bedliner on top of the Lizard Skin. Heat is not an issue(if you remember, I coated both the bottom and top of my trans tunnel with Lizard Skin. Very little heat on my truck. Had that goofy gold reflective heat barrier on it too. Maybe that's what makes it reject all the heat. ha.
I think.....if you really wanted to......you could lay that Spectrum on nice and thick, let it cure really well and probably sand off just the top to smooth it down. Maybe drag a skim coat of it back across it to fill in any low spots or voids. Sand again. The more sanding of course, the more you lose of it's properties to insulate and kill sound but you would get a smooth finish. You may be able to use a squeegee to apply it very smooth. It's super easy to work with and no real right or wrong way to do it. Whatever works. We almost never spray it any longer.
On the roof(and a few firewalls)I have been using Second Skin Audio's Heat Wave Pro....which is a jute material with foil on both sides. We use contact adhesive to hold this to the Spectrum. The Heat Wave Pro is great stuff. I did a firewall in one of the 79s and it was great......zero heat in that truck. The factory sound deadener had fallen apart....so we used our butyl stuff, Spectrum, Heat Wave. I would probably do an LV with it but I'd probably install one of the firewall covers on top of it. Just to cover it up.
Second Skin sells a product called Luxury Liner Pro....it's a mass loaded vinyl(MLV) that is amazing. If you're going to do carpet, this is what you want under it. This stuff deadens ALL the noise....incredible. But it requires full coverage...no gaps anywhere and again, you'd want to run carpet on it. We use a lot of this in our builds.
Hope that helps!
