I've got a few seeds that I was gifted from a guy way up north in Canada. He said he'd take the seed and toss a few in various places around the cows pastures andd take what popped up. He said that he had been doing that for 20+ years before jumping on the boards and gifting a few of those seeds out. He lived at 50N & in Ontario if i recall correctly. Plants displayed dark magenta purple hairs on dark green BLD plants with a fairly short stature. At 38N the plants act like auto flowering varieties out doors and will not revert to veg state. I doubt there is any ruderalis in these genetics as D. didn't know anything about autoflowers. I don't recall when he said he would harvest but probably mid to end of Sept would be a good guess.I'm at 48 parallel Canada, somewhere on this planet the 20 years old genetic exist always, I'm like you, I'm searching that, for the moment I work with early genetics that have ruderalis in, and I don't like that so much.
This sounds exactly like what you are looking for, IMO.
The variety was given the name Royal Purple. I don't thin you will find much info on it other than what is posted at skunk mag forums, but they're not free to read.