I would NOT leave him on the porch, especially with winter fast approaching. I would crate train him. If he is pottying in his crate, his crate is too big. You need to make the crate as small as possible so he cannot go potty in one end and lay down in the other. Even if you buy the smallest crate you can find, it can still be too big. You need to make it smaller by putting cardboard boxes or tupperware in the back to make the crate smaller. Here is the best method I have found to potty train a puppy using the crate:
http://www.darnfar.com/Dog%20Trainin...ng_a_puppy.htm
If you are consistent and do it exactly like this article suggests, he will be housebroken in no time. Also neutering him will help with the housebreaking. You can get him neutered as early as 4 months of age.