I found this out on VRplaYK's verifier tips for speedrunners, in the 2nd post under number 10, mentions that you can use Sodium + Phosphor + Lithium for 1.16.

Yea Phosphor and Lithium can be used alongside Sodium in 1.16+

If you still want to play Minecraft and see your timer on one monitor/screen, you can make Minecraft borderless windowed mode and go fullscreen from there. Download ThatFlashCat's "BorderlessMinecraft" program or find another one, it's the one I use for streaming and speedrunning Minecraft on a laptop.

Also for IGT, look at Resources and choose one of the timers shown there. I chose Kohru's Livesplit extension for my IGT but all of them should be good to use.

Good luck on speedrunning :)

No, using a boat to negate fall damage (by MLGing or rowing off an edge) is not a glitch, so it's okay to use it for RSG.

If you're talking about trapping the enderman in a boat for it to not move/teleport, no. Killing an enderman sitting on a boat is not a glitch.