I grew Jack Herer photos from Emery Seeds about fourteen years ago. Been hunting it ever since. Princess 99 photo is another solid incarnation of Jack. Old Sativa Seedbank(Now merged with Nirvana) put together Jock Horror photo that was my go-to strain for the past six years or so. I've done a lot of photo breeding so playing with autos, once I realized what they were capable of, became a focus of mine. I will choose a male from the MsA x JaHe's & MsA x RoJa's to cross back to Jock Horror next year. Then mix the resulting offspring back to JaHe or RoJa. I have a vision for autos with good traits capable of becoming a land race here in Alaska without human assistance. I don't suppose you know anything about Danish autos?
Have no idea about Danish autos. Except I imagine that they'd have to finish off pretty fast to survive outdoors there!
But your breeding plan sounds very good.
I'd keep the JaHe and RoJa lines separate at first.
They may both be JH based, but could be fairly distinct.
Maybe run two lines to stabilize, then create a F1 between them.
Then the distinct Herer qualities should come out. Without getting recessive.
Just a thought.........