Below is a rough outline of the ice tank size & placement I am planning. I don't want to put it in the spare tire well because that deep space is useful for so many other things. So I am going to put it on the "shelf" toward the front of the car right between the wheels. This area is impossible to access with the roof stowed anyway.

trunk3tank-1.jpg

Warning: I have an SLK32 AMG. That is what I am building the ice tank to fit. If you have an SRT6 or C32 AMG and are want an ice tank also, someone will need to verify the dimensions. The picture below shows what I measured for the SLK32 AMG. These are the maximum exterior dimensions of the tank. It will fit underneath the luggage tarp, be as deep as possible without overhanging the spare tire well, and will set between the places in the front corners of the trunk floor where it raises up at an angle. This gives 3.5" on either side for the fittings, and flanges to secure the tank to the trunk floor.

trunk3dimensioned-1.jpg