When you say, "we are long-time travelers, and have never been successful in packing light," do you mean you've traveled a lot or that your trips tend to be for many nights? Or both?
Most on the forums are committed to light packing, but many are not. As has been mentioned, the basic RS philosophy is something along the lines of "you schlep what you bring." This is not so important if you take a city tour and stay in the same hotel the whole time. But then, most of those tours are so short, a person doesn't need much anyway.
I've been on 5 RS tours so far and am considering pairing the Basque Country of Spain & France in 9 Days tour with Best of Ireland in 14 Days next year. I'll be 74 when I do that.
I travel solo, and have been offered help of various kinds on the tours. I always appreciate it, and sometimes accept it, but being a stubborn sort, I believe I should be able to manage on my own. Packing light is one way I maximize the probability of not often being dependent on others.
Many people, whether on RS tours or not, pack lighter than I do. Packing for a week and doing laundry along the way make it possible for me to pack light and still have lots of wardrobe combinations so long as the major garments coordinate with each other and I take a little jewelry and a scarf.
Since this is your first post here, I'm going to list some links on this website that might be helpful for you to learn about ways to lighten the load and make it more likely for you to seriously consider an RS tour.
Packing Light. All the basics with more links.
Sarah Murdoch's Packing Light & Right. A travel talk well worth watching in its entirety.
Packing Forum. Lots of advice and opinion on what to pack, how to pack, what luggage to use -- you get the idea.