Actually, this looks fairly simple to texture. The main hull doesn't have a very pronounced curvature at the edges, so there won't be much warping. The secondary hull isn't weirdly curved, so you can simply divide it in four lengthwise and get a good top, bottom, left and right. Those are Sovereign engines, so those should already have texture sets that you can either map to, or they should have come pre-textured from whatever ship you got them from.