Welcome aboard!
As others have observed, 50 MPG is a challenging goal, but... "what's a heaven for?" You've made a great start by adjusting the nut behind the wheel, and things will continue to get better as you refine your technique and make useful mods.
You're welcome to join
Team Nissan and, speaking of which, TOOQIKK's Sippy (a '94 Sentra) has turned in 45 MPG+ tanks. So that at least should be within your reach. (Heck, I've managed 40 MPG on a few tanks in my chunky-by-comparison Versa hatchback... and with no aero mods to date.)
Regardless, have at it and have fun! Even if you never crack that magical 50 MPG barrier, you'll surely benefit from your efforts and from the learning process.
Cheers,
Rick