If it's the same paint and all that is all you can ask for, shoot it. A test panel isn't going to do anything as it likely won't be sprayed EXACTLY the same as you would spray the cars parts anyway. It's just human nature, it takes a bunch of study to shoot exactly the same, you are over thinking it. No matter what you do, unless you just shot the previous part next to it a minute ago, you are over thinking it and will likely do something different. But with the same paint and all you are WAY heading in the right direction. That is realistically all you can do at this point.
I have watched one of the painters at work shoot test panels for color and I want to scream. He shoots this little piece of paper he is holding in his hand MUCH wetter than ANYONE would shoot the fender on a car. His spray out panel is WORTHLESS because of this. I have explained this to him and he still bombs the color on the test panel coat over coat one two three four in seconds, COMPLETELY different than how the car would be painted. And he wonders why his colors don't match, drives me CRAZY.
But it's human nature that you MUST overcome, it's very hard to apply that paint on a test panel the same way.
One thing is for sure you want the panels you are now spraying to be in the same "attitude" as the adjacent panels were painted. In other words you want the hood and trunk you are now shooting to be on a rack sitting exactly the same as they will be bolted on the car. Not hanging like a pair of blue jeans on a clothes line, laying down just as they are bolted on the car. After all, you didn't have the car hanging from the rear bumper when you painted the rear of the car where the trunk will bolt right? No, you had the car sitting there just as it will be driven. So your painting the area surrounding the trunk lid was horizontal, that is how you need to shoot the trunk, just as if it was sitting on the car.