UI Canvas with split Camera

I'm developing a game with single mode and local multiplayer mode (2-4 players) , so, for each player i have a camera, and i modify dynamically the Viewport Rect according to the number of players, to make split screen in multiplayer mode.

And I've a Canvas prefab that is instantiate dynamically one time if there is one player or 2-4 times for multiplayer.

My doubt is about adjust the canvas rect with the camera size in multiplayer mode, i've tried setting Canvas Render Mode to "Screen Space - Camera", and the canvas fits well with each camera for each player, but since the camera is 3D, all the canvas elements looks like 3D elements, so this is not a solution.

Anyone have some idea about how to approach this?