I am going to try and explain it in test to go with the pics..
What you are trying to do on the front is make 3 tape sections with 1.5" tape. 2 and the upper section and 1 at the lower.
Make 6 vertical lines front. 1 at the edge where the upper control upright is, another at the "end" of the that straight section one at the bottom 45 degrees off the top and another at the "end" of that piece and then another 45 degrees up to the next section and the lat one at the edge of the opposite upper control arm upright.
Then with 2 the 45 degree angles from the bottom one up to the top 2 use 2" tape and set it up to hit the vertical lines.
On the back you will have to use the same principle, but it isn't easy to use 45 degrees, you can use 60 degrees but the tape has to be close to 1.3"wide ran at that angle.
The ones below are at 45 degrees using 1.5" and 2" wide tape, and we scribed the bottom with a 1.5" wide curve to allow it to sit down flush
If you do it this way it sits right down with no gaps. ( I always kept the "humps" in mine)
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