1. It sounds like you have about 200 pounds of stuff at the very back plus your weight wherever you sit. Try walking to the very front of the boat and look over the side to see how it sits. My guess is it will level out a lot and tell you to consider redistributing the weight.
2. Just moving the battery from the back to the front will remove about 45 pounds from the back and add it to the front, a net shift of 90 pounds. This points out that moving anything forward even a little bit can have an effect.
3. Once you are underway you can use engine trim to bring the boat to a more level position.
4. Many pontoon boats have a visible water line mark on the logs. Look at others and compare it to yours if that matters to you.