The only practical way to have any kind of cislunar habitat is going to be utilizing lunar water for cosmic ray shielding lifted from the poles using 20 to 25 times less energy than from Earth. Since a capsule would require around 400 tons any acceptable amount of living space for even a small crew is going to mass well over a thousand tons of just water to start with. A true space station would not only protect against dosing but also debilitation with tether-generated artificial gravity. The definition of “true” being a Near Sea Level Radiation 1 Gravity environment (NSLR1G).
It follows the only practical way to place these kinds of water-shielded compartments into space is a double-hulled “fat” wet workshop since this will already be stressed for one gravity and the outer propellent layer can handily contain the water shield. These Fat Workshops are going to require an even more powerful iteration of the SLS than is being considered now lifting well over the 130 metric tons specified. And of course the critical hardware is a semi-expendable Robot Lunar Lander that can convert lunar ice into propellant and make as many trips as possible bringing water up.
Once a pipeline for these true space stations is operating then docked landers can be used as propulsion modules to allow Lunar Cycler operations and a fleet of Cyclers will create a constant flow of personnel and materials to and from the Moon. Each one of these several Space Stations and likely half a dozen or more Cyclers would mass several thousand tons and a state sponsored program of expanded SLS launches the only practical way to establish this permanent Cislunar human presence and infrastructure. Space “entrepreneurs” are not going to do it.
Out of all the hardware listed such as the Super Heavy Lift Vehicle (SLS) and Fat Workshop and Robot Lunar Lander, the most important piece of the puzzle missing is a cryogenic propellent engine in the 2 million pound thrust range. Either that or the unlikely option of a much greener solid fuel booster. When this F-1 class SHLV engine appears it will be a signal we are ready to commit to a real space program.
Ice on the Moon 