Question about PCI-E gold finger fanout
I've never had to do this on any PCIe, Mini PCIe or M.2 card I've ever built.

Bring short, wide traces from the GND fingers to the interior of the board, and drop the vias to the GND plane there. There's still ample room to get the signal pairs past these vias.

Below is an example. Note that the vias are shared with GND pins top and bottom.