tractor weights

I have been trying to get some leadheadz, but unfortunately i probably wont get them becasue of costums in Mexico. I was thinking about getting some tractor weights put in the bow of the 2002 x star, they are supposed to be 45 kilos or 99 pounds each and measure 14 by 16 inches. I have not seen the weights, and have not measured the space under the bow seats in my boat because it is at the lake. Has anyone done this to a similar boat. I would be putting three of those plates in each sideof the bow. a total of 594lb in the bow. if any one has done something similar please tell me how you set them. thanks!