...try an auto parts store.
Greetings driver- I've had good tape producs (ie. servo tape) bought from the auto parts store.
3M brand Door strip moulding tape is like servo tape. But since you've bought the outdoor tape ( with the 5lb rating ), try it.
Jus consider G forces as you are driving the car around. You don't want Electronics dragging on the ground when physics acts upon your car.
Good Luck.