Weight is a force: f = ma & gravity is an acceleration, so weight = mass * acceleration but this should be a ratio: weight = mass * environment_gravity / 9.81 m/s. For convenience, orbit should be weightless.
A 200kg mass weighs 200kg on Earth/Kerbin but 33.2 kg on the Mun. In a low g vacuum, the mass is mostly weightless. So you can more easily displace the mass in orbit and on the Mun, than on Kerbin, because your kerbals are able to do more work (displacement of mass) with the same effort (energy). Hence, the mass carrying capacity should change relative to the kerbal's environment: weight carrying capacity = mass * environment_gravity / 9.81 m/s.
The only catch is that the more mass a kerbal carries, the more energy (eva rcs) the kerbal expends regardless of environment.
I want my kerbals to carry two jet packs in orbit and on the Mun, but not on Eve, Kerbin, Tylo, etc. Please fix.