Galaf

Here's the CROSS: It has 9 stages, including the LV-N which is attached to a docking port. I let Mechjeb fly this until ~55km before I switched over to smart A.S.S. and set it to 5 degrees above the horizon. Achieves a payload fraction of 36.24/195.61 = 18.52% Also delivers a fully functional cargo: An orange tank with a mechjeb unit, 4 solar panels, reaction wheels and a docking port. Why not use it to start off a space station? You could probably squeeze out the FL-T200's by playing around with the engines and flight path, but I can't be bothered. Abusing cubic struts and 48-7S's is another possible improvement, but I consider that cheaty even if the rules would allow it. Even with those tweaks, I think it's impossible to hit a 20% payload fraction.