my dresser holds a 47g but its 4ft long and the tank is only 32" long but the dresser is 17" wide and the tank is 18" its been there for months until i closed the tank down to sell it lol
i believe you can fill it all the way.
i put a 30lg on a'desk' that is 6'' smaller then the tank so 3'' on each side was sticking out.and the desk is made from .5-75'' wood.also the sides only were supportting the weight of the tank.