Ignore the battery monitor's idea of when the AGMs are full. EG the Trimetric has a 1-2% of capacity as " full" except they require you to set an AH capacity. Unfortunately that capacity is highly variable with temperature and over time with age and condition of the batts. So it is fairly bogus right there, plus AGMs require amps to taper to 1/2 of 1% at 14.4v before they are full. So the Tri is out to lunch on that too.
With a Tri, you just use your AH counter and your own existing estimate of bank capacity and do your own math for the SOC. Also do a cross check with voltage per SOC for your battery's spec allowing that you can't get quite to actual "resting" voltage while camping with always some low amp RV draw. You know when it is at its lowest draw, so use that--close enough! (ie wait till after the furnace is off for now and turn off the lights.)
Sometimes the AH count and the voltage don't "match" for what the SOC should be. This is a clue that you need to do some checking on the situation. Sometimes that is because the AH counter needs resetting. You must kill the auto reset if you have solar for instance.
I never try to get the AGMs or even the Wets truly full when camping off grid. You can't run the generator that long. On solar you run out of daylight. Just do what you can (50-90s eg) and wait till you have shore power and all kinds of time. Now you can go for the 0.5a/100AH using your Tri as the ammeter for noting when you get down to that 0.5a per.
It will take hours and hours to get there. The AGMs will not heat up doing that.
It sounds like that Samlex charger with its options will not do what you need, and also IMO you are mis-interpreting what Trojan says.
See 5.22 for AGMs here: Nothing there about two hour limits! It says absorption ends when it gets down to 0.5. No time limit.
https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdfGood thing you are on here asking, though. Proves that you have a clue!
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1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.