HI,
It would seem that the success of a manned mars mission would depend on
sending the required material ahead, landing some of it on the surface where we intend to land our mission, as well as landing enough SRB components to aid in launching a vehicle from Mars' surface and rendezvous with a Mars orbiter,
and refueling THAT in orbit as well.
You still have to beat your extended low gravity problem as well as
the extended exposure to radiation.
Advanced vehicles to orbit helps to solve many problems....extra parts,
filters, fresh water, food, medical, etc.
No one said it would be cheap, convenient or without risk.
Sure is the most expensive gravel in memory, but....it gets you into the
great book of records.
Toseek is right ! You need to have a perfect handle on Men in LEO before you ponder Mars. No question.

Best regards, Dan