How to frame the side cantilever joist for deck?
Add 2 or 3 blocks perpendicular to the joists directly under the post locations. The longer the block are the better to minimize splitting when you run the post mounting screws into them.

You may already plan to, but you can move the posts over the last joist to get a little more room on your deck.

When the mounting screws go through the decking, sandwiching everything up will be quite strong.

But this does only address the strength of the railing. The joists must attach to the ledger, no "floating" joists