Not so fast...AGM's are not sensitive to high charging current
...some of the TPPL AGMs can accept a charging rate as high as C; e.g., a 210 amp-hr battery
can accept a charge rate up to 210 amps.
Howerver, they are very, very sensitive to high charging voltage and charging voltage is a function of, among other things, temperature. The TPPL AGMs that I am most familiar with specify +/- 4 mV/degree C/cell from 25C. This becomes 24 mV/degree C for a 12 volt battery.
As an example: At 25C (77F) nominal float would be 13.62 VDC and nominal absorption voltage would be 14.70 VDC. At 40C (104F, not uncommon), the nominal float voltage is 13.26 VDC and the nominal absorption voltage is 14.34 VDC.
For your batteries' sake, spend the $40 for a temperature sensor for each and every one of your charging sources.