I got some black vinal of ebay to do a couple of stipes on the gfs car, It just takes alittle time and is easy to do. I started applying it whilst holding the other end up then used a blockbuster card (other rarely used credit type cards would also work) to help work the vinal down, making sure prevent air bubbles, a cloth may come in handy as the card can scratch the vinal if not careful.
Id be tempted to start in the middle and work one way leaving the backing on the other half. The work it up to the corner as close as possible then use a stanley blade to trim to size. Id also prob work along the top then pull it round to do the bottom.
It may be worthwhile getting 0.5m too much so that you can have a bit of a pratice. As can easily pull if off
Any big air bubbles peirce with the stanley blade to help squeeze out air.
Just takes a little time