I didn't see a schematic but maybe I was looking in the wrong place?
I know you can make ethernet connections via traces on a board (this is how PINE64's Clusterboard works) but I believe you need to have transcevers on both ends before you drop-down to traces.
That's part of the reason I was considering other interconnects because it seems like a lot of extra hardware, but OTOH it's simple and proven, so...