Madone wheel and tire recommendations for rough terrain road race

I’m planning on doing a road race in norcal, Copperopolis (called the Paris Roubaix of California), that has very rough concrete / gravel (as seen on youtube and read in various comments). I have a 2018 Trek Madone 9.0 (rim brakes and stock wheelset):

A few threads I’ve read and videos I’ve watched are recommending 28s w/ lower pressure for the race. The link above has a couple comments asking about 28s on the Madone but Trek responds that they recommend a max of 25. Has anybody mounted 28s or larger on a Madone? Which wheels and tires did you use? Ultimately, what’s the best way to know the largest tires that my bike and wheelset can support?

I own a 2020 Trek Madone SLR6 Disk with Bontrager Aeolus pro 5 wheels and Bontrager R3 Hard-Case (25s). I inflate them to 8 Bar (116 PSI) …never had a puncture or any other issue.