I really like the idea of this!

My recommendation would to start it with him already on the job looking for the Child. You can set up that he’s searching for a 50 year old bounty in the crawl, have him land, meet Kuiil, then have your opening act action be the battle alongside IG-11. I’d cut down his hunting down the Jawas, maybe even find a way that he just returns to the stripped ship and then has to go deal with the mudhorn. I’d then try to transition as quickly as you can from the major elements of chapter 3 to the stuff from chapter 4, and maybe have him recruit Cara Dune before leaving (cutting out all of their other travels). Then you’re set back up for the third act.