Sir: The reason a man will go is in order for him to "do" what only he can do
and then to return that individual or crew.....back to earth.

There is really no point in sending man on a one-way junket at exhorbitant expense to the martian surface and that's it. It is far cheaper to set him down in death valley and let him enjoy the experience there.
The point of going into space is to accomplish something tangible .

Of course,......such scrutiny begs the whole question of ' going to mars '
in the first place .

But the OP is the difficulties involved in that endeavour. It's discussion is purely acedemic, which I enjoy.
When you finally see the entire scheme laid out end to end, it will be far more
complex and expensive than you have imagined thus far.
At which point it will be left to question: "Is it worth it? "

Best regards, Dan