Matt,You asked for suggestions. If people give you the free advice that you asked for, you don't have to take it. At the same time, if you just rebut them flat out, people will not want to offer you ideas.
I suggest looking at the JPL design. Biprop stages, 100kw SEP, blunt-body lander. It relies on SLS' EUS for departure but I guess more biprop stages would do the job as well.Here's the paper for the lander:https://trs.jpl.nasa.gov/bitstream/handle/2014/45916/15-5417_A1b.pdf?sequence=1&isAllowed=yEdit: Ah well, 25t launcher, not an option then
Using only the 'cheapest' classes of launchers available for the next 8-to-10 years - 15-to-25 ton class <snip>Phase 1: Earth orbit testing of vehicles and hardware.Phase 2: A high Lunar-orbit deep space 'shakedown'.Phase 3: The manned Mars mission. If successful; there may be a second mission with a slightly longer surface stay next time - primarily, the second mission is just to ameliorate the expenditure and investment on the first. A third mission would likely occur as an obsolete artifact when the big SpaceX vehicles finally get going, probably a few years later than planned.