A simple improvement of the interconnect is using two rows of pin headers, one rows for signals and another rows for dedicated grounds. This should significantl

A simple improvement of the interconnect is using two rows of pin headers, one rows for signals and another rows for dedicated grounds. This should significantly reduce the loop area. I once did a quick simulation and found that even controlled impedance is somewhat possible with 1.27 mm headers, although I haven't done any experiment with it (yet)... Another possible modification is converting all I/Os to differential signaling before they leave the board, a classic use is eliminating the radiation from long ribbon cables. Ribbon cables with ground planes also do exist if one's willing to pay...