Made a quick entry for the light category with a payload of 11.84t. The insights re: costs of solid boosters for career mode were interesting, though I think I'd go with two solid booster stages and a larger recoverable circularization stage in practice. It also had around 600m dV left in the circularization stage in a 100km orbit, so obviously things could be optimized more. Stats: Total cost: 36,198 Payload cost:15,460 Lifter cost: 20,738 Payload fraction: 6.0% Payload mass: 11.84t Cost per t: 1,751.52 The "Can o' boom" lifter: