Harry I would try to get the battery up under the fuel tank if you can. Put foam between the tank and the battery. And wrap the whole thing in foam. My Tiger II has a standard 600 mah battery under the tank. Works just fine. It is better to move the battery (if possible) than add weight (but you know that already). With the battery under the tank you may be able to eliminate some or all the added weight. BTW good choice on the battery. If ya gotta add weight, may as well add functional weight. Good luck with your Tiger.

Mark Shuman