Another mad idea, we had already plenty of those.
What if someone came along putting $ 500m on the table, proposing to go on the very first cargo ship to Mars? Mabe 2 persons like Inspiration Mars.
This is assuming that the pressurized space would already be there with temperature control and the solar panels. Inspiration Mars was proposed with the FH 13t to Mars including Dragon and habitat. Assuming 15t for a similar ECLSS including supplies should be on the safe side for the needs until the second ship with crew arrives.
Maybe the assumption is wrong that pressure and temperature would continue to be controlled during the stay on Mars. That would require a pressurized volume for that period. A closed volume for the ECLSS to maintain breathable atmosphere might be needed anyway. They could go around the whole pressurized space with a simple oxygen mask or a system that recycles the breathing air while outside.
Any chance at all that Elon could be convinced to agree?