Parallax series 7300 converter question

I am replacing a Parallax 7345 with a Progressive Dynamics 4645 (float 13.2V). The Parallax floated the batteries at 13.8 volts. My concern is Lifeline recommends 13.0-13.3 volts in warm to hot temperatures and I was frequently having to shut off converter or disconnect batteries-or at least I believed I had to... Example of my camping is week in Zion in summer plugged in Watchman campground.

Curious to what is the damaging effects on AGM batteries for operating at higher than recommended float voltage in higher temperatures?