Terrible skunk smell

Does the smell seem to be coming from the shower area? If you haven't used it, the trap may be dry which would leave it open from smells to come from the gray water tank. Put some water down the shower drain if that is the case. You may wish to use a gray water treatment as well. I would hope you have water in the sink trap and the bowl of your toilet also to make sure those are sealed also.

Another possibility is that the vent pipe was not connected properly to the vent on the roof that is supposed to vent odors to outside the pod. That happened with the first motor home my parents had.

A third possibility is that the base of the toilet was not sealed properly. Given your statement that it smells like a porta-potty, I would suspect the vent pipe or the toilet seal. In any case, it would be a good idea to take it to your dealer if adding water to the drains does not eliminate this.

have you used the sinks, and shower? if not, the p traps can dry out..