I decided to use the Auveco #10780 spring type fastener because I thought it might have more holding power than the Auveco 12134. Now that I am finished I can say the #10780 worked very well. That Magdaddy idea looks cool, too.
Here is the finished install. The area I was trying to secure is the upper left hand corner.
I attached this aluminum tab with two machine screws. It is very stout!
Then I installed the spring fastener to the panel board I used to fab the upholstered panel.
This view gives you an idea how the spring clip slips into the hole I drilled into the mounting tab. Just one push and the clip holds the panel very nicely. When you need to remove the panel you pull on the panel to disengage the clip.
Many thanks to the guys that offered your suggestions.
I was hung up as to how I should secure this corner but after your suggestions I was able to complete my trunk in a couple of hours.