Some of my favorite conservative sci-fi writers would have to include David Drake’s Hammer’s Slammers series (and his other works); Robert Adams’ The Horseclans series and; Adams’ “Stairway to Forever.” I never finished the 2nd Adams’ series, but from what I remember it started off very conservative.
I have not read much Sci-Fi fantasy in years and have probably enjoyed many stories regardless of their political affiliation, but w/out a more comprehensive search of my memory/library those come to mind as good examples of conservative sci-fi writing in the past.
In addition to classics like CS Lewis and Tolkien of course. Even LeGuin’s Earthsea series I would characterize as conservative in it’s social mores.
A long time ago, at Dragon Con IIRC, Robert Adams told a us a tale at a panel:
Being badly hung-over from the previous night of drinking, he came into a morning panel and said something to the effect of “Isn’t it pity that we spend more effort improving breeds of cattle than we do improving the human race.”
The fans took over from there and he took a nap.