Not sure what you mean about staying away from "harmonics 1-10"
But if there are no chips on the board the main issues in running differential traces, which i assume you are working with at 5 GHz, is to control the impedance and maintain matched length. If the board is just running traces between connectors and you have control over the placement, put the connectors parallel and assign pins that do not require crossovers. Then matched length is simple. Vias are also of concern at 5 GHz. So these traces are ok.
/------
-----/ /-----
------/
These traces are not
o------
------/-------
-----o
Different lengths and unmatched vias, or vias at all if you can avoid them.
Some may talk about avoiding sharp corners which creates a tiny lumped capacitance. This may not be a big factor at 5 GHz, but that is possibly the threshold of it being significant, so to be on the safe side use 45 degree corners which have less of a problem. Or you can get all RF like and use round corners. Just make sure everything is symmetrical on the two lines of the differential pair.
There should be plenty of references on running differential controlled impedance traces. It has particular requirements, but it's not rocket science.