[Delete Wrong Section] Water/Weather proof/resistant distance sensor (no lasers)

I have built a prototype rig that measures the height of a vehicle going over an object at point 1 using a Ping))) ultrasonic sensor and then again at point 2 using another Ping))) ultrasonic sensor. I then use the height and the millis() between the edge readings (the sensor goes from maxing out to getting a vehicle height reading) to determine the time it takes to travel the defined distance. All the data is sent to our program and we calculate the vehicle speed and height off of that, which we use to calculate various things in our application. This all works great but these ultrasonics are not weather proof, so if it rains I'm sure everything will short out and if it doesn't the water will mess the readings up.

We've looked into waterproof ultrasonics but none of these meet the minimum/maximum distance requirements needed to measure a vehicle's height as all the sensors I have found start at at least 20cm (just under 8 inches) where many cars are 8-ish cm from our testing. Not sure what other sensors are available that might work lasers are off the table due to business requirements.

I've been searching for a while and I just can't find anything that I think will work, hoping someone might know about a sensor I haven't stumbled upon yet.

The only hope I have is this sensor http://pulsedlight3d.com/sensors/ (when it is released next month hopefully) might do the trick. One setup they are releasing uses LED light to detect distance, but I don't like putting all hope in 1 option if it isn't necessary.

Any help would be much appreciated.

Thank You!

Sorry don't know how but I posted this in the wrong thread. Tried to delete but it says I can't.