I don't think 1" will be weak & IF you can judge each board for clearness (no knots or sapwood) they will prob. last fine. IME 5/4 or thicker boards would simply last longer because they would be more forgiving if there is a defect.
I used 3/4 kiln dried oak boards on my covered front porch & they are plenty strong enough.
... sorry, I should have read the whole thread closer.
