Dead is around 11.8V and 50% is 12.2V on most batteries.
The Duralast and Trojan's are on separate systems correct?
As for the voltage, the reading while they are being used is not what an indication of state of charge. There needs to be no/minimal draw on the batteries for a while before they "bounce" back from use to get a good idea of the voltage. They may drop to 12.27 while the heater is on but will come back up an soon as it goes off and indicate the actual voltage.
On my previous battery setup I would drop down to 11.7-11.8 while the heater (7-8 amps) was running but 5 min later I would be at 12.3 indication a little more than 50% charge.
My math tells me that you should get about 24 hours at a 7 amp draw on the Duralast batteries and have a 50% charge.
As for the solar panels you need to ensure they don't get any shadows on them, and have large enough wiring to transmit the power they generate. Most kits come with undersized wiring, and/or the controller is placed too far from the batteries.
