Agree with finding out what happened on the only 2 years. (Though I know sometimes this can be self inflicted
The rest comes down to the math on how much your willing to spend. A few comments:
> Assume this is two tays of 4 batteries each? If so then you could have a restriction on headroom(?).
> Assume the Travel Supreme has a sophisticated enough charging system to support AGM's(?).
> You don't mention the controller with our solar panel, but hopefully it to can handle AGM's(?).
> As mentioned AGM Lifelines are one way to go. Fullriver is also obtaining fans, at lower buy in point. As you know, and as mentioned, AGM's provide you with zero maintenance and also can be recharged faster. (Mention the recharge faster, due to the stated intention to improve boon docking. Faster recharge, can get you back to 100% possibly with all solar. Or AM generator, and then top off with solar.)
> If you decide budget wise you'd prefer to stay with wet cells. Then Trojans would be my first choice. And, I'd include a water management system at the same time, if you don't already have one.
> Regardless of whether AGM or Wet, get your battery tray dimensions, and available headroom. And then check the charts of the battery manufactures for which of the batteries will fit into the locations. (For example, if staying with wet cells, and you have enough headroom - Trojan T145's will fit in the same foot print as the T105's - and provide more AH capacity. On the AGM's, say Lifelines. And you have the room for them the L16's are a beast of a battery, and have close to the same foot print as many normal 6V's.
It really is a matter of your current, or if you want to spend more coin, modified battery compartment space. The rest is just doing the math on battery dimensions to see what will fit. And, how much you want to spend
Best of luck to you,
(Note: We do have X's 4 Lifeline L16's, in place of our OEM X's 2 8D's. 800AH's. Our 1200 Watts of solar, does a pretty good job of keeping them charged during dry camping. Been happy with these combo's for the last 4 or so years now. When they go? I'll swap over to lithium, and keep the same 800 AH size, but due to lower discharge rates of the lithium's this will be close to a 75% increase in my useable SOC.)