How much would Dragon 2 or Red Dragon need to be changed to act as a lunar lander? What I mean is not just landing but also lifting off from the Moon's surface to a specified orbit to dock with another spacecraft.
The current designs would need some modification. For a Moon mission the heat shield and the parachute system are unnecessary, so in place of their mass there could be fuel available for the mission. But would it have enough fuel to land and bring the astronauts back to orbit? If not, how much more fuel is needed? What would the total mass be for this? Also what kind of other modifications would it need, for example life support systems, internal power, and spacecraft components (computers, electronics, batteries), protection from radiation, and structural material changes with lighter materials (since it will not serve to make a re-entry into Earth's atmosphere just as a lunar lander)?
This will be costly, since the design could change, but would it be worth it to modify the current Dragon spacecrafts, or would it be better to create an entirely new design with better capabilities for such a mission and that doesn't resemble the current designs?