You may also want to check the voltage at the converter terminals and at the battery. It wont make the wfco work any better but you may have more voltage drop than realized which will hurt your charge time no matter what converter you use. I have a PD4655 but if I did it again I'd buy the boondocker that goes to 14.8 volts. I put an 80 amp boondocker in my sons FW. His battery and power center are 30 feet away each other so I mounted the converter next to his two GC2 batteries and ran new romex back to the power center. 80 amps is just fine and will also do better if a person goes to four batteries later on.
There is basically nothing wrong with your sams gp24 but they are just minimal capacity. If the battery in the truck is a plain automotive battery it isn't intended to be run down like a gp/marine /RV battery. You may do a lot better by running two GC2 if they fit or get two gp27 or 29. I use gp 27 in some non RV applications and they work well but they are not GC2 true deep cycle. To me it seems that the gp are less forgiving and more susceptible when not fully charged each day. You dont have to do a complete charge every day but as the days go on the gp battery will fade in performance faster than a deep cycle gc2. Just my opinion.
I use four sams gp27 in series for 48 volts and do regular charges at 60 to 61 volts. I'm not recommending that for everyone but I would shoot for 14.8 and depending on wire size and distance most likely end up seeing 14.4 to 14.7 or so at the battery. As you mentioned, check the SG and if needed get some other charger to fully charge the two gp24 until you see good SG.
In my thinking no matter what the RV I wouldn't use the tow vehicle or MH charging system to charge the house batteries. I dont want any isolator or possibilities of trouble when I want to drive away. And again if the battery up under the hood is an auto type battery it isn't designed to cycle up and down like a Group or deep cycle. If they intend for any battery under the hood to help out with carrying the RV then it needs to be a Gp battery or better.
A mega watt power supply is a cheap way to have an extra charger on hand which can also equalize which is what you may need for those gp 24 right now. A Meanwell is an even better quality power supply but be sure either one will go to a high enough voltage for equalizing. I bought this
one 13.5 to 18 volts The other day someone also posted what I would think is an even better power supply which has a volt and amp adjustment with meter.
If you cant possibly get four or more batteries in your given space you dont need an 80 amp model converter but
smaller models are available.
This is what I installed in my sons FW but the battery box that I built can also hold four GC2 in the future.
