I've done a repair like this before. It can be done in one piece of covering. The trick is to use your heat gun for application and stretch the covering at the same time you are shrinking it. Iron the covering down without shrinking it on the flat part of the wing, stopping where the curve at the leading edge starts to tighten. Then you can pull on the covering at the front to stretch it as you use the heat gun to activate the adhesive. That will pull most of the wrinkles out of that annoying section between the spar and leading edge on the wingtip. Then use the same pulling technique to adhere the covering to the edge of the wingtip by wrapping the covering around and pulling from the bottom while heating the top. You'll need to aim the heat away from the first seam you made, so you'll need a glove to protect your hand. Once it's stuck all the way around, you can keep using the heat gun to wrap the covering around the radius of the wingtip. The last step, if needed, is to use the iron at shrinking temperature to shrink out any looseness that remains over the open structure.