150 lbs for the boat and 150 lbs for the trailer should not be a problem as long as you do not have too much weight inside the car. For both pulling and braking. The car is designed to haul four people plus belongings. Reduce weight inside your car to make up for the trailer. At highway speeds you may feel some extra drag from extra wind resistance. Most car manufacturers say to not allow your car to go into overdrive when pulling a trailer.
To have a lighter trailer consider buying an aluminum trailer. Aluminum is one-fifth the weight of steel.