There is a similar system offered on the good side of the border, but instead of a wifi signal it just uses a sensor attached to the back of a target that is wired to a camera flash a suitable distance away. The flash is easily observed when the target is struck. there are drawbacks to them and one of them I can see being a problem for your set-up.
The sensor that attaches to the target receives a very violent energy transfer when a bullet strikes. Solid attachment and a ready supply of replacement sensors is requisite for them. the second concern for the flash system wont be a concern for yours I don't think, that being a very good guard system for the wiring & flash body...you would be amazed how bullet splash can torture exposed parts ( I lent my system to a fellow shooter one time...he had to replace it with a new one). If you do get your wifi unit to work reliably under a constant beating it is going to have to endure It will for certain have a commercial value to it.