Many thanks guys for all the response. It does seem that I'm heading down a well trodden path. At the end of the day the only real protection is going to come from decent crash bar protection--but I've had a look at the frame and it wouldn't be easy to generate something that won't fold back into the tank on impact--has anyone done this?
I think that if the carbon guards are siliconed into position, and they wrap round the front of the tank a bit, they won't come off in a mild impact and the silicone will provide a good buffer to allow a bit of flex--I reckon three layers should be adequate--but we'll see. My "mark 2s" will wrap round more on the LHS for stiffness for the petcock protection extension. I also intend to provide enough of a cut out to operate the tap when on the move--I get about a mile from the reserve light flashing to actually running out--quite accurate! --its going to be a compromise--and its effectiveness is something I hope I don't test!
I'm sticking with polyester and will use teflon coated peel wrap for the inner finish--so far I don't have a wetting problem with polyester--and you don't want to be too cold otherwise it can affect the curing process. I tend to precut all my sheets and work quickly!
I'll post pics when finished--mine will go higher than the Jap version and will also have some styling curves to the side--they will go back to at least the first tank hole--going back much further isn't worth it as the tank sides drop away--I started the moulds with a crash damaged tank from a friend so you get a good idea of what hits.
One final comment--the only way the petcock is going to get it is if you bounce on a rock or it hits a rock when sliding on its side--does this happen?
The Dakar has started--all the KTM 660s don't seem to carry any side protection?