SXT Sixpack and 3 offices

Hello!
Ive got SXT Sixpack and next task. We have permanent wired link (link 1) between Main office and office 2. But this link is unstable and sometimes down (rent). I want to make reserved chanel with Wi-Fi and OSPF. And we need permanent link between office 2 and office 3. There isnt direct visibility between Main office and office 3. But it is between main and 2; between 2 and 3. In office 3 supposed to use wireless clients, in office 2 only wired.
I think that OmniTIK U-5HnD should to be in the middle. Or not?
So what modes on SXT 5HnD and OmniTIK U-5HnD you advise?
SXT 5HnD have 3 level license.
План Wi-Fi.jpeg

Yes, Omnitik should bi on the pole in office 2 in AP mode and SXT’s in main office and office 3 in station modes (or station-bridge if you want multicast helper to work).

Thank you. I`ll rty it.