If you did a stretched SS tanker optimized for orbit—50t dry mass, so that's no flaps, TPS, and shed the nose to reduce mass—it could deliver ~750t to a LSS in that 2.5km/s elliptical orbit, vs ~635t. This easily closes for a LSS with a slightly stretched tank (80t LSS with 20t cargo, tank adding 200t additional props). In fact it could take more cargo.