Spooner, when I had my shop in 80's on Hwy1 I saw a LOT of over loaded road bikes. From basic steel rimmed Peugeots and Schwinns with Pletscher racks to road bikes with sewups and Blackburn racks. Heavy guys broke rear wheels, heavy rear loads broke rear wheels, small tires and heavy loads caused more flat and rim damage than bigger tires. People who did their own bike repairs didn't overload, road carefully or had durable wheels. Nowadays entry level bikes have stronger wheels and the big tubed aluminum frames on entry level bikes are better load carriers so you're probably starting off with more leeway than riders in the past.
Just ride and see what works, don't let anything get loose that's supposed to be tight or tied down.