Ok, this is only thinking loudly.

There are many ways to save weight in a vehicle meant for the moon (after all, the idea of having astronauts standing in the LM rather than sitting, saved the Moon program!).

First: every astronaut wears his spacesuit (even at launch) and not a pressure suit plus later a spacesuit (obvious).
Then, why not reduce cabin pressure and with only oxygen (while in space, not on the ground nor on the moon station)?
Then, forget windows (small cameras can do a great job and more than one can be placed outside) and forget dashboards, screens, switches, etc...use screens in the helmet or on the arm, use virtual reality gloves.
Remove the seats after MECO and put them back right before re-entry (for room, inside).

Because the trip would last less than 3 days, (or 7 days back and forth) there really is no need for much room, food , water or oxygen.
At launch, go from zero to 11 km/sec (or TLI) in one go, without cutting off the engines, therefore without need to restart the engine in 0G (this required the SIVB stages to be surrounded by little rockets being ignited for the purpose of pushing LH2 and LO2 into the engine).

Landing on the Moon: use an unpressurized (separate) landing vehicle or use the same vehicle as the one you are in during the entire trip (minus the launch rocket of course) and land with it on the Moon.

Of course, engineers think first about what is needed when the vehicle lands back on Earth (astronauts alive and well) and from there, go back to all the operations required for a trip to the Moon.

These are just ideas.

Raoul