Yeah you might have to add 2 strips and then trim one of them down to size, though i think you will be fine with just 1 strip of the stuff.
The tape i have are also not as wide as some cameras sticky pad, but i just put on a single piece as it is too fiddly to add another one beside and then trim it to size, and just 1 piece have been fine for me.
Since my buddy was not able to help me with getting more magnets i have been searching today, and there seem to be a massive difference in price, the cheapest local place i have found i can get 4 magnets for the price of 1 similar sized magnet the most expensive place.
So will be ordering 10 Magnets as soon as i get my piggy bank emptied into my bank account when the damn bank open.
I was not able to route the rear camera of my Viofo A139 system above the headliner this past Saturday, i damn near ruined it all instead and was only able to push the wire on a thin ALU rod 3/4 of the way thru.
So went along the sides and then this summer i will take the whole damn headliner out of my car, and then put some cable ducting in before i replace it, but still not able to go strait across the headliner.
Its also okay just not mentally and weather minded for a bigger job right now, the length of the wire for the A139 rear camera + my small car, i could route it forward first around the engine and then out back and still have wire to spare.