I'm skimming the book now.
Dobby's burial is probably the only place to end it. It has some closure.

After that, the second part can begin with the plotting of the Gringotts break-in. Still in Shell Cottage, talking to Griphook and Olivander and each other, that leaves lots of room for the screen writers to refresh the audience before the final roller-coaster begins.

From Gringotts through the final nod from Dumbledore's portrait was all one, seemless day. No way to break it up.