How important is a files infil when printing with TPE?

I am printing a fursuit base out of TPE and the file is completely hollow since its a mask. It has only the walls which are around 4mm thick with one wall and hex infill if that makes sense? It's hard to explain tbh I hope I'm making sense. I'll include a drawing of what I mean.

Now my question is, is TPE sturdy enough to keep the shape that way and not cave in, or does the model need to be completely solid? (With hex infill I mean).

I really hope this makes sense, all help appreciated.