The trick to avoid registering is the length of time you are away from YOUr ADDRESS. Pay close attention this gets tricky:
We are allowed to be on vacation 6 days and under WITHOUT registering. However, the clock starts when you physically leave your house.
For example, when I go to NY, I leave 3:00 pm Thursday eve. If I do not want to report it, I have to be physically AT MY HOUSE, not on my way , Wednesday at 6pm.
To prove what time you left and got back, stop at the closest gas station and buy gas. Keep your receipt. YOU HAVE to be able to PROVE when you left and got back. So buy some gas when you leave and come back.
IMPORTANT TO have a receip.