I haven't kept track much on how feasible the Starship rocket is. Maybe it's not that hard to make fuel on mars. Maybe humanity is making good progress figuring out how to transfer fuel in space. You sound much more educated than me on the advancements being made.

I still think it would way more feasible to just to find 5-6 guys in the 25-30 year range to send on a one-way expedition. Instead of spending all of their time maintaining a factory making fuel these guys could be spending time exploring the planet and doing experiments. In return humanity would memorialize them and try to send them stuff to stay alive. After a few years we would try to send another crew to join the first crew to make more progress on the planet and build from there.