I typed 1:6 batwing into google to see if anyone had been crazy enough to try building one, and yep, sure enough..
He posted under the alias of batman_taiwan
That is some mad skill and dedication, and it looks like he made a batmobile too..
It gives us an idea of what size it could be, but I would say if HT made it, it could be a touch bigger even.. and again in person it would be alot bigger than it seems in photos.. displaying nightmare.. but that's what top shelves are for