I like the approach of going back to the old ABO language and amending the enforcement spot provision. There are a couple of minor edits I'd make for language such as the All But One principle not being defined anywhere, and the general voice of that section is off (the future tense is awkward, "ABO will be used...").
I'm not sure I agree with the Section 6, Article 2 exceptions - they are not in line with the current rule. There are a few exceptions that remain spot fouls now, not a short listing of those that go back to the previous spot. I'd be worried something would slip through the cracks.
My philosophical take would turn it into a slightly modified ABO:
1) Define the basic spots as you have, including the 5-3a provision about runs ending behind the line of scrimmage.
2) Add the current 10-4-4 a-d (skipping e) as a subsection of Special Enforcement (current 10-5) where these fouls are always enforced from the spot of the foul.
3) Unless the modified 10-5 applies, any foul that occurs behind the line of scrimmage, prior to a change of possession, is enforced from the previous spot
4) Unless the modified 10-5 applies, enforce all remaining fouls using the previous ABO definition