Experiment with that trailer. Maybe you can remove or lower the sides for less wind resistance. Make sure the wheel bearings are clean & greesed if you can, load the weight low & keep it on the light side too. Load it and go for a Saturday run, maybe 40 miles or so. I'm kinda a stickler for proper braking power, so check it out.
With that many commuting miles your legs should be in real good shape for 60 miles.
Once your on the road stop every ten miles or so not only for the rest & stretching but to check over the equipment, mainly the trailer hitch.