In a rapidly rotating environment, if you pour a drink it will go sideways… or turn your head and it will so disturb your inner ear you get extreme vertigo and nausea. It is called canal sickness and why very long tethers are really the only practical option for artificial gravity. Simply walking and operating hand tools also pose challenges
Rotating room experiments have shown doing even common tasks becomes progressively more difficult as rotation rates increase. Even as little as 2 RPM seriously affect efficiency and requires habituation, and of course rehabilitation upon return to real gravity. This is why a very good benchmark is 1 rpm. If you go to the artificial gravity spin calculator site and plug in lunar gravity and 1 rpm you get a radius of about 500 feet or a 1000 foot tether system. I say system because it would likely be multiple tethers with lesser movable masses to tune out oscillation. A crew compartment with an equal mass at the other end of that tether system is what you would need to simulate lunar gravity in space. To provide 1G and eliminate debilitation the tether system would be about 6000 feet long. To shield a small capsule from cosmic radiation to eliminate dosing would require a minimum of 400 tons of plastic or about 500 tons of more utilitarian water shielding. Providing practical long duration living space, for even a crew of two on an exploration mission, this shielding would go well over a thousand tons, though this water would provide medium for closed loop life support.. So for a true Spaceship, maybe capable of a Ceres mission, IF some efficient Nuclear Electric propulsion is developed, the ship will mass several thousand tons. Since nobody is going to sign off on the damage a mission Beyond Earth and Lunar Orbit without a Near Sea Level Radiation 1 Gravity environment will do to a crew, this makes a joke out of Musk’s Mars fantasy.
Ice on the Moon 