I talked to the person Clarke Manufacturing today. They have had a lot of requests for an auxiliary tank for both the country and the challenge. They are going to take a serious look at it. Sounds like they are confident they could bring it in for a far more reasonable price than the TT tank. I think enough people emailing them would help sway their decision. I think $300 for a 2.5 gallon would be sweet.
I for one don't think that adding the weight up front is bad. Especially if you are planning to carry other gear on the back of the bike. Having the added fuel load up front instead of at the tail will balance the load better, versus having the added fuel ang gear at the tail.