cmogletree-
This is possible to do in Method but will require a bit of work to get this to work the way you want it to.
Right now when you map from the Work Order List it checks to see if the shipping address is blank and if it is it will use the billing address to generate the stops (This is done on a per work order basis in a loop).
You could take that existing logic and have it add both the ship and bill address to the action result it uses to plot the addresses(resultAddressList).
Since from the sounds of it you added some new fields to the Activity table for the address soyou will also have to make sure to update the actions to reference these new fields.
-Michael