In your original post, your problem is killing the battery overnight with only the refrigerator running on LP. Your parasitic drain has been measured at 0.3 amps. I don't know which refrigerator you have, but my Dometic with aux cooling fan has a 3 amp DC fuse. So it uses something less than 3 amps when on LP gas. But let's use 3 amps to stay on the long side.
So at night you are drawing down the battery at a rate of 3.3 amps (3+ 0.3) for approximately 10 hours. Or, 30.3 amp hours.
The specification for the battery you pictured (when new) indicates your battery should be able to produce a reserve capacity of 160 min (2.7 Hrs). The industry standard for reserve capacity measurements is at 25 amps. So... 2.7 Hrs X 25 amps = 67.5 amp hours of capacity.
As an aside....This was probably the cheapest (and lowest Amp Hour) battery the dealer could have installed.
Flooded lead acid batteries become damaged when fully discharged. My personal view is never draw one down below 50%, but some use 80%.
So lets go long and say that if you draw the battery down to 80% you will have used 54 amp hours. This is still considerably less than the 30.3 amp hours necessary for overnight use. In fact only 56% of what should be available to you.
So, it is highly probable your original battery has experienced damaging sulfation and isn't capable of holding a full charge any longer. If you are interested in learning about what happens when sulfation occurs, you can read this article.
https://www.power-sonic.com/blog/what-is-a-sulfated-battery-and-how-do-you-prevent-it/
My recommendation is to ditch the old battery and also add battery capacity. You can have two 12 volt batteries in parallel, or two 6 volt golf cart batteries in series (many use two
Trojan T105 batteries which have 186 Amp Hour capacity). Which ever way you decide to go, I would recommend looking for batteries with higher a reserve capacity than what you have. If they don't list Amp Hour Capacity they will surely list Reserve Capacity in minutes. Just divide that number by 60 and then multiply the result by 25 amps to get Amp Hours.
Though these days I use lithium, in the past I have had both two Interstate SHM-24 batteries (81 Amp Hour each) as well as a pair of Trojan T105. In either case performance has been good.
I hope that helps.