On the topic of the cargo liner, I have the same prob, except I have two 90 lb dogs. I am also fearful that their weight will crack the cover over the spare.

The rubber cargo covers are not what I want because the dogs will slide around pretty bad.

I'm thinking of just taking 3/4 inch plywood and cutting to the shape of the cargo cover, drill the hole and put a loop in it to pull it up and carpet the thing with some nice thick carpet so the dogs don't slide and will be comfy. Then just put a little flap on the front end that can roll up over the seats when they are folded down. Any thoughts?

 

I finally found a great site for the liners thanks to a member's help...
Check out www.hunterk9.com

I think I am going to go with this one http://www.hunterk9.com/site/870877/product/CANINE23
Its a little expensive, but it is offered in several different colors so I can match and looks real comfy for my guys!

As for the spare cover... I never really checked it, but definitely will now seeing as one of my guys is 100+ lbs!!
In the past I have taken the tailgate cover piece... flipped and roated it then just put it in the back of the trunk (over the spare wheel cover).
I didn't do it to prevent him from cracking it, just because it was the easiest solution for me... I live in Manhattan so I don't have a garage I can just leave it in... but I guess that in doing that I have protected the spare cover b/c everytime he gets in/out he is jumping and I am sure he would have cracked it by now if it is going to crack at all...

Hope that helps!