Forge floor materials?

[TNF]

Hello, 

I'm new to the site so I hope I chose the correct section to ask this. 

I'm in the process of constructing a new ribbon burner forge. I have all the components/materials purchased except what I'm going to line the floor with. 

The forge design is similar to the Essential Craftsman's ribbon burner forge....but half the size (I know it's going to be big but I have working coming in that calls for large hammered truss plates for a timber framer plus other various large projects) I don't want to make a monolithic forge so I plan to line the shell with 2 inches of ceramic blanket, then a coat of metrikote.

The floor is stumping me. I've contacted Wayne Coe regarding the floor and he advised me to not use hard firebrick because it will act as a heat sink. I don't have many options for the floor because of the design so I'm wondering what would be a better option?

1. 2x1" layers of ceramic blanket, then topping it off with 3/4 kiln shelf. 

2. One layer of ceramic blanket and then lining the entire base with soft firebrick, with a top coat of  metrikote. 

I'm open to any other suggestions. The tray holding the floor materials is approx. 2 1/2" deep. 

Thanks. 

[Irondragon Forge ClayWorks]

For a replaceable floor number (1) High alumina kiln shelf will work well. In our forge (a 20 pound propane tank) we used a heavy coat of bubble alumina (Kast-O-Lite 30) over the blanket but it's not replaceable.

[TNF]

I had considered kastolite but I cannot find anyone near where I live who sells it.  I can order some in from Alberta but the s&h is a lot.  I do have a few bags of mizzou but I found out after buying it that it's not a great insulator. 

Does anyone have alot of experience using the kiln shelves? When they start to crack or fail, can they be patched with anything?