Look what I came up with after the previous post and it turns out I made a card by accident. I was just testing the cut and came upon this (unfinished, but is starting to be a great watermelon card!) The file is available below and instructions for the liner as well.
The scallop side will overlap the other fold by about an inch or you could shrink to meet in the software.
To cut the card turn off the eye to the New Layer (can we rename these in the 2.3.2?)
To cut only the liner like the red in the sample picture turn off the eye in the default layer as shawn below.
(in the file I did rotate the liner and changed it to a different color to keep from confusing it from the card itself.