Tilt Alarm for 2015 Prius that uses existing keyless entry system

I'm trying to find the easiest and most reliable way to add a tilt sensor to my 2015 Prius that utilizes only the existing keyless entry system. I have no other alarm on the car now. The solutions I have revolve around the DEI 507M tilt sensor. If you know of any other decent options, please let me know. I seem to come to these two options:

1) Install the DEI 507M tilt sensor. Use the "car off" and "doors locked", signals to turn on the alarm after some delay (with a 555 timer or such). I don't know if the DEI 507M would have to be "debounced" or not. I have the least information for this option. I don't have any wiring schematics of the car, nor do I know the signal voltage levels (all 12V?).

2) Buy a PT398-47090 (RS3200+) factory alarm with glass break and door opening, alarm/sensors for about $125. It's supposed to be plug and play to the existing wiring. I think it needs to be programmed with techstream to match up key fob to the alarm (Will a Mini-VCI cable work for this?). I'm not sure if the alarm would be set by locking the car with the door handle option which is an important ease of use item. Does anyone know? After all of that, one can add the 507M tilt sensor to extra sensor inputs on the alarm module??