You’d be surprised what they’ll cover in terms of Mods. Especially OEM mods of course. The reps there are very understanding or at least they were with me twice lolWhy would they ask anything? It is in their interest to collect a monthly payment based on the VIN provided. They wont simply cover what you added unless it is known to them. If you keep receipts for the regular maintenance that was done that will help ensure that you get the max if something happens to the stock configuration
For reference I have USAA too and they did not ask me about my 4Runner either.