floor Insulation

I have seen many threads about installing the insulation on the interior floors to slow down the heat. I planned on doing that to my 74 and now the 72 as well. I also saw a car show on ESPN that featured a product called Lizard Skin. I found it on Summit Racing site and bought it and the gun to spray it. My question is, is it really needed to spray or insulate the back compartment behind the seats? I really never felt heat from there. seemed as though all the heat was from under the dash and off the floor boards. Just looking to see if anyone else had done just the front. Hope to hear what others have done and how it worked out, as I plan on spraying the lizard skin on tomorrow or Tuesday night.
Thanks
Rodney

True, most of the heat seeps in from the front area, but doing the rear compartment floor will also help...just not as much as doing the front. Be careful of any wiring or fiber-optic lines anywhere, when spraying....

Spent the last 2 nights removing everything in the front compartment and taping everything up,  then tonight I sprayed the ceramic base lizard skin. Tomorrow I plan on installing the foil back insulation and by sometime this weekend I hope to have everything back together and go for a drive. I'll let everyone know if the lizard skin + insulation makes a difference. I did take some pics and If I figure out how to put them on here I will. 

The insulation spray is still a little wet in the corners tonight so I will wait until tomorrow night to put in the foil insulation. Still plan on a drive this weekend!