" * Apollo CM. Other Designations: Command Module. Part of: Apollo CSM. Class: Manned. Type: Spacecraft Module.

Crew Size: 3. Length: 3.47 m (11.38 ft). Basic Diameter: 3.90 m (12.70 ft). Maximum Diameter: 3.90 m (12.70 ft). Habitable Volume: 6.17 m3. Mass: 5 806 kg (12 800 lb). Structure Mass: 1 567 kg (3 454 lb). Heat Shield Mass: 848 kg (1 869 lb). Reaction Control System: 400 kg (880 lb). Recovery Equipment: 245 kg (540 lb). Navigation Equipment: 505 kg (1 113 lb). Telemetry Equipment: 200 kg (440 lb). Electrical Equipment: 700 kg (1 540 lb). Communications Systems: 100 kg (220 lb). Crew Seats and Provisions: 550 kg (1 210 lb). Crew mass: 216 kg (476 lb). Miscellaneous Contingency: 200 kg (440 lb). Environmental Control System: 200 kg (440 lb). RCS Coarse No x Thrust: 12 x 410 N. RCS Propellants: N2O4/UDMH. RCS Isp: 290 sec. RCS Impulse: 257 kgf-sec. Main Engine Propellants: n/a. Main Engine Propellants: 75 kg (165 lb). L/D Hypersonic: 0.30. Electrical System: Batteries. Electric System: 20.00 kWh. Battery: 1 000.00 Ah. "
http://www.astronautix.com/craft/apolocsm.htm

Command module weighed about 6 tons.
If you wanted to fly around the Moon [not go into orbit]. And you wanted to replace the probe instead of adding to it. And you are sending 1 or 2 crew. And you designed as bare boned as possible. A lunar transfer payload of around 3 tons might be possible. But 4 or 5 tons might be more reasonable- which the Russians, Sea launch, French, Indians, and/or Chinese could do.