As for your solar panel charging issue, my first thought is charging voltage. For 12v batteries a charge voltage is around 14 v. What do you get from your solar setup?
Trojan T105 batteries that Phoenix installed on my rig indicates on their data sheets, at least 14.8v to charge and 15.5V to equalize your batteries and 13.2V float after fully charged.
Most solar charge controllers are set up to do this correctly. Your 110-12v converter is not.
Also as noted all 6 volt batteries are almost 11" high, so that the tray must be lowered if your rig was built for 12v batteries. After April 2012 I believe Phoenix did this.
What happens to most campers is that their batteries never get fully charge so they observe that they don't get out the amp-hours that they believe they should.