Thanks Mex, that is clear enough. I now believe I can risk using the 55 amp converter set to the Float voltage for the AGM. If it ever does the higher than 27 amps in my possible scenarios, it won't be for long and not in extreme ambients.
Meanwhile I have consulted Mark's temp comp table he posted here a while back, and set the converter to Float at 13.9v to meet the 13.6 to 13.8 range in the AGM's float spec. His table says 13.6 at 25C is 13.9 at 12C which is about average here this time of year. I can go higher when it gets colder.
Scroll down to his post here
http://forums.trailerlife.com/index.cfm/fuseaction/thread/tid/26669731/srt/pa/pging/1/page/1.cfmThanks for all the help everyone, I am a nervous newbie AGM guy now. You probably helped some other folks checking this out too.