You cannot bring that bag on board
I'm struggling to understand the grammar of this sentence. I'm aware that you can make the humble form of a verb by adding an お onto the masu-stem and then adding する. I assumed that is what was going on here. So we have 持ち込む --> お持ち込みする
Turning する into できる seems okay to make the potential form. But then we also seem to be treating the お持ち込み as an independent noun. I'm happy that masu-stems can be used as nouns but what's troubling me is that none of that humble form structure we made has remained unscathed. In a plain sentence I would have just said 機内に持ち込むことができない (is that okay?).
I'm happy with the への part (田中への手紙 etc) but I don't understand why it is necessary here. Why not simply 機内にお持ち込みはできません as in my plain example?
I guess I'm also nervous about the は in the middle of お持ち込みはできません. It makes me think that may my analysis of it being the humble verb form is completely wrong.
Anyway I'm rambling now. The bottom line is that I have no idea how to parse this sentence correctly. Could someone please explain the grammar and provide some additional simple examples?