Instead of usig a solidering iron i highly suggest getting access to a hot air station. i soldered smd before but never this small.
Hats off to ANYONE soldering these, thats serious skill. im using my hot air station on them

May i ask what's the safe temperature setting when soldering these using hot air station? I plan to use hot air station as well but i'm not so experienced on this stuff yet..
You wanna use Kapton tape to cover the SMT units and just leave the exposed area. Kapton tape it's a heat resistant tape, so its perfect for hot air solder. Use experiment on a dummy board before using it on your GDS units.