Strange question.....

So I'm going to be putting in a rear seat delete not because I race it or anything but it's not used except my dog. The rear delete makes it flat so I can put a bed down. Which brings me to the question.

The rear seat deletes are for weight reduction and will supposedly not support any weight back there. Would I be able to buy/fabricate a thicker board or supports? Any ideas appriciated....
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My dogs a 75lbs american pitbull so she's a little chunky but loves the car so the kits more for her than anything lol
 
For your purposes, I think I would get a couple of large pieces of cardboard or poster board, pull the rear seat and make a stencil pattern...test fit in the car...then transfer it to plywood (3/8" would probably support your dog if you support it). Also, you might consider placing some insulation (foam or fiberglass) under the horizontal board to isolate your dog a bit from heat and vibration. I think I'd just paint the horizontal piece of plywood and toss a dog pad, old blanket or some towels in there for the dog to sit on...easy to pull out and clean...the vertical piece could be painted or carpeted. Cheers!