Been done before
chuck the Russians a few Million dollars, and buy the Energia design, use that as the basis and develop it.
or do likewise with ESA and Ariene 5,
complete? no, but a good starting point.
or dust of the NERVA project...
use a Saturn-VI (saturn-V with better controls and fuels) as a heavy lifter, something smaller and simpler as a crew launcher, that *just* puts people up and down, let the truck do the heavy stuff.
the problem is not doing it, its doing it god alone knows how many times, in different groups.
ideal solution.. use something based on Soyuz as a crew launcher/lander. need to launch more than three people? use more than one of them.
use Ariene as a heavy lifter, again in multiple if needed.
let the yanks design the stuff they carry.
then get the Chinese to build it, or at least the common production run bits.
don't commission *one* of something, make a run larger to get some economies of scale.
stop buggering about with space planes, KISS.