I just installed an Aeromotive Stealth in a tank tonight. Aeromotive Phantom 340 Stealth Fuel Systems 18688 You dont need to cut the trunk floor. Just space the tank down. I plan on adding length to my tank straps if they are a tight fit.
You can get those big rubber mats from tractor supply. Use what you need and the rest can be used as cushion in front of your workbench. The mats are used in horse stalls, I believe. 4 ft. x 6 ft. x 3/4 in. Thick Rubber Stall Mat at Tractor Supply Co.