IIf you don't mind seeing their name spread all across the stuff. If you don't want to see advertising, NOICO is only a buck or so higher in silver, or another buck higher in black. I've used the .080 thickness in black, on 3 vehicles now. It sticks well to the metal, and isn't bad to work with, as long as the area isn't too confined. You have to roll it out with a roller to complete the job, sand that hand held roller is 1" in diameter.

For heat insulation, you need to cover every inch of the metal surface. If the OP is just covering the areas under the seat, none of that stuff will be an effective heat barrier. Vibration, yes, heat barrier, nope.

For the guy asking about weight, a 36 SQ Ft package of NOICO weighs somewhere around 17 lbs. I have 2 packages of the .080 36 SQ FT packages inside of the cab of my 49 Dodge truck, everything is covered except the inside of the doors. There was not enough material to cover the insides of both doors, and getting that stuff inside of those doors would have been a huge challenge.

Picture of the truck for cab size reference. Gene.