Thanks to everyone for the comments. It sounds like my original plan is not a good idea. How about plan B--which would be to run a wire from the neutral at the light fixture back to the switch box and connect to the neutral on the Wemo switch. Same circuit, and obviously, same switch-light combo.

To answer the question above, the switch and outlet box are on separate circuits.

Thanks, everyone. To clarify, the switch will draw minimal power. The switch and outlet are on two different circuits, each nowhere close to being overloaded. There are no GFCIs on either circuit. As for code, the residence is in Brasil where code is virtually non existent. However, it is new construction with what appears to be an excellent electrical installation and ample amperage in the main box. I would remove the neutral if I sell the house, although a new owner is unlikely to install anything other than a light switch in a switch box. Any other suggestions would be welcome.