If I were going to try to straighten a strut I would be inclined to make a jig that incorporates a hydraulic "porta power" ram or bottle jack, because I don't think you could get enough force out of a screw type. It all depends on where on the strut the bend is, but I would start with a thick steel plate that acts as a base for the hydraulic ram. You could then use long bolts or reddi rod to connect the base plate to flat bars that brace the opposite side of the strut on either side of the bend. The hydraulic ram could then be positioned to apply force on the bend without placing any force on the hull connection itself.
I would definitely try straightening the strut on the boat before I considered removing the strut completely. If it breaks? Well then it needed fixing anyway!