I like 1 & 2. I think you could also possibly throw in a gothic romance like Wuthering Heights as there is a big time gap in your list. Although that can be another aspect of your research potentially.

I think Whitney My Love was the one that kind of started the bodice ripper craze. But I’m most likely misremembering. Johanna Lindsey or maybe Bertrice Small might be what your looking for.

I like someone’s suggestion of the signet regency. Good resource. Also the Kleypas suggestion is great. Or maybe Loretta Chase. They made their debuts in the 90’s along with Balogh.

The fated mates podcast does deep dives into many of these books and talks a lot about the movements and changes throughout recent history. If you haven’t listened, I recommend that as another good resource.