Multiplayer RTS: Rendering a specific mesh for multiple cameras

Hi there, I'm making an multilayer RTS game. The way I'm trying to implement my game is each player gets their own camera and only allied units are rendered for that camera. I can accomplish this by giving the "RedCamera" a culling mask consisting of only the "RedUnit" layer but I need to be able to see other units when they are within range. The camera is able to pan around but enemy units need to only appear when in a certain range of ally unit(s). I could always set the culling for the "BlueUnit" layer to on for the "RedCamera" whenever a specific blue unit falls within the range of a red unit. But, if I do that every Blue unit with the "BlueUnit" layer mask will appear regardless if that individual is in the view range.

I originally thought I could tackle this by giving each individual unit a layer mask ie: BlueUnit1,BlueUnit2,ect but that seems inefficient and there's a max of 31 layers (I think).

The only other idea I can think of is giving every unit several meshes of the exact same thing and then just disabling and enabling the specific unit's mesh if it falls within a distance. But I'm planning on giving unit's different weapons and lots of children and I can imagine this being taxing (not sure though).

So what I would like to know is if there is a different angle to tackle my problem that I'm not aware of or if I should try giving each of my units a mesh accounting for each of the player's camera.

Thanks in advance