One of two things. Maybe both. One option, and this is if you have a flat jon, not a mod vee, is to replace your bow roller with a bow stop that goes almost all the way across. This can be as simple as a 2 x 4 covered with carpet.
The other is to strengthen that area of the boat. On many jons, (my 1542 included) the more vertical spot on the front is not as thick as I feel it should be. That is where much of the pressure is when powerloading, and often, there is a handle up there that the winch attaches to. This can be solved by riveting a piece of 3/16 aluminum on top of the existing aluminum with 3/16 diameter, 1/2 inch grip length pop rivets.