Gravity API:
https://www.curseforge.com/minecraft/mc-mods/gravityapi
View rotates as it should, though each eye seems to be offset from normal Vivecraft.
Eye height also goes into the block below you occasionally.

Same issue, but more specifically: it seems that when gravity is changed, Vivecraft assumes the head's camera should have the standard Y level offset from the player's feet. This causes the player to have their camera bug into walls sometimes because the player's feet are effectively clipping through a wall. This Y level offset also presents the issue of getting stuck on objects; I assume this happens because you should be falling based on where your player-model should be, but isn't falling due to where Vivecraft assumes the model is.

Integrating with this mod will need some significant rewrites to room positioning code, so it's gonna have to go on the back burner for now.