Here is one more vote that says you are on a good path. I think I see where you are going - Blend the best of both worlds. Use the lines of classic vintage era models or any date full size sailplane. Take some liberties to fudge the dimensions just enough to make the aspect rations and moment arms similar to today’s winners. Now put on a modern airfoil and install a modern radio to get all the cool mixing and tight controls. Use modern construction methods (ala bubble dancer, etc.) with carbon to keep the weight down. You’d have an eye pleaser that would fly like a dream. I don’t think the bigger fuselage cross section will harm much at all.