Generally not required but some configs may benefit especially if the load rocks forward and aft. The parking bunks are there to stop movement not to really carry a large load. In some cases the parking bunks stop the keel from hitting a cross member. There are other option also, a bow V or a roller or perhaps a bumper pad. You have to see how the boat loads, unloads and moves when towed.
If trailer set up and sized correctly often the bow stop off of the winch post is sufficient.