I think him slaughtering Tusken Raiders is enough going dark for one long movie. It’s explaining what happened to Dooku that would be your problem.
In my version Anakin and Padme will never go to Tatooine. We won’t hear from them until Obi-Wan sends his alert from Geonosis. Throughout this reedit I’m treating Anakin as a supporting character; the story proper will focus on Obi-Wan’s personal experience of the Republic’s fall.
One thing that occurred to me today is to plant a semi-explanatory seed in the revised crawl, making Palpatine already the Republic’s chancellor, and mentioning that there’ve already been abduction attempts. Therefore later seeing him needing to be rescued (as far as the Jedi know) won’t be surprising.