Solidify material offset

Hello,

I use two different materials (1 and 2) on the outside face of a mesh, a ‘solidify’ modifier and a third material (3) on the inside face (with the material offset function).

Problem: I want to have the third material on the whole internal face and the offset principle does not allow it:
each of the two external materials (1 and 2) applies the same offset on the inner face and returns either 2 and 3 (material offset:1), or 3 and 1 (material offset:2).

Is there a way around the problem without applying the modifier (I’m watching my polycount) or duplicating it to apply to two separate vertex groups - which also seems unnecessarily complicated?

((I imagine Geonodes can do it but it’s a bit convoluted))

Edit: You just need to place the inner material in last position and set the offset to 2 or more (if more materials); it will pick the latest material in the list.