Well the reason that TW wouldn't really be good for Inf is that the defenders are supposed to "defend". If you had a TW map, you would mostly just have a wide open space that the attackers had to cross to get to the defenders. Unless you made almost all of the defensive positions in the defender's favor, so attackers could use foxholes but defenders would get towers. I don't think anyone has made any, try to make a beta map and see if it works.