John, the BD (British and elsewhere deck) is only 26'6" in length, and only 5 feet wide.  My deck will be smaller, only about 20' long and will be made from sheets of foam like that which I already buy for making foam cores.  For right now I will only be using the take off portion (unless I get really into this project, at which point I may make the arresting area as well. Because there will be no need to walk on the deck I see no reason why foam sheets will not work well.  They come with plastic sheet covering, so fuel exhaust should not cause any problems.
Personally I think the raised deck makes a lot of sense.
Joe