Getting back to this ... I ordered the Brigitte as well as these very very light chamois panties:
https://www.clubrideapparel.com/collections/innerwear-women/products/jewel?variant=960734133
They both arrived today. I wasn't thrilled with the Brigitte - for my preference, they came down way too low in the front, and the chamois was wide enough that I thought it might result in the same chafing issue I've had. But really it was more the waistband being so low.
The Club Ride panties, though, I'm pretty excited about. They fit more like my regular panties do, and the chamois is tiny - well, they advertise it for 1 hour rides, so of course it is - and it doesn't touch my thighs. It's about as thick as a modestly thick panty liner, maybe. Just a touch of cushion. I've been wearing no chamois at all the last few weeks, and haven't been noticing my sit bones, but I figure this might be about right for me. Plus I like the look better than the stripes on the Brigitte. I have a 12 mile cross country out and back tomorrow, so I guess I'll have a chance to test them out!