How to connect Go Set a Watchman with To Kill A Mockingbird

As we conclude our reading of To Kill a Mockingbird, how do we make sense of Harper Lee's Go Set a Watchman rough draft?

Here are my thoughts:

Quick Timeline1) Harper Lee writes GSAW, but publisher doesn't think the book will sell
2) GSAW become a rough draft of TKAM, which Harper Lee writes after returning to Alabama
3) The new book trades ambiguity and questions for nostalgia and simplicity to get published

How can I prove my thesis? 1) TKAM is a dual narrative, 1st person, reflection on the 1930's
2) GSAW is a 3rd person, present unpacking of the 1950's

Here's the thematic center of TKAM:"First of all," [Atticus] said, "if you can learn a simple trick, Scout, you'll get along a lot better with all kinds of folks. You never really understand a person until you consider things from his point of view […] until you climb into his skin and walk around in it" (39)

Here's the thematic center of GSAW:“it’s always easy to look back and see what we were, yesterday, ten years ago. It is hard to see what we are. If you can master that trick, you’ll get along” (269)

Thesis Statement: 

Harper Lee adapted GSAW and its insistence to deal with the present into TKAM's saccharine reflection on sympathy.