@shermer what buses are you thinking of?
there isnt a great deal serving dartmoor and princetown is about as big as it gets on’t moor…if you want transport links then look closer to ivybridge, tavistock, bovey tracy or oke…
afaik there is a bus to princetown.
you can walk from oke to princetown in a day, then carry on to ivybridge the next day completing the dartmoor north to south, Ive done it a few times, its a nice walk.