Can Pekin Bantams Free Range?

One more silly question - I know that Pekins carry low to the ground and have feathers on their legs.  I read that mud is a real problem for them.  We are planning to let ours free range in our small back garden in good weather.  How serious is this mud problem?  If we leave their house and the garage open during the day, will they know to come in out of the rain if it happens?  Sometimes I can be thick as a brick.  I just want to make everything as right for them as possible.