At 1600#s I would go with a dual axle. Weight placement is a bit more forgiving and I find they track better. Backing up is easier with a dual axle also (at least I find...). Down side, you need 4 tires instead of 2 but tires are cheap compared to the boat itself. You can use the other tire/wheel to pick up the trailer to change a tire but using a small block and back or pull onto it. It will lift the other wheel off the ground.
JMO,
Clayton