Will you make it so when you disable the backpack rendering with elytra, you could do the same for capes? So when you have a cape enabled the backpack doesn't render

// Render backpack if elytra is present
	"renderBackpackWithElytra": false,

Or as an alternative: a separate config option that disables the cape whilst wearing a backpack?

Not going to do that, added config option to disable whole backpack rendering though
https://www.curseforge.com/minecraft/mc-mods/travelers-backpack-fabric/files/all