The Space Shuttle is the second most powerful LV after the Saturn V (at least one that works). The problem is that in order to launch payload such as Destiny, it must also launch large delta wings, a huge tail fin, a luxurious habitable volume, landing gear, recloseable payload bay structure propellents for de-orbit and a thermal protection system for reentry. Remove all this crap and the LV has the capability to launch something nearly as cool as Skylab.
So here's the plan. Cut off the forward bit of the orbiter and stick a large spacecraft there instead. In one go, we have something with nearly the same capacity as the ISS at present.