Springback may be limited by heating the bent piece. Example: when bending banjo rims of .25 hard maple stock I will leave the bent piece clamped on the form and heat to 120 F and hold for it at that temp overnight. I use a large wood box heated with a light bulb. I do understand that the length of gunwales may be awkward. If somebody really wanted to make an effort to control springback then only the bent end clamped to a form would need to be placed in a heated environment to "set" the bend.