at the moment im working on the layout for the pcb. I decided to use smd components as you can see in this picture: 

With these smd components i can get the hole thing fit below the HC-SR04 sensor. But still i need a double sided PCB, and ony have exposed pads as programming port...

But on the otherhand beacause the PCB is that small it will be very cheap to manufacture in china :)