In addition to all the good advice above, I would add this, get a battery with removable caps so that the electrolyte can be topped up with distilled water. In hot climates, this should be done annually.
Now I see that you don’t get a year from your batteries, so next, I recommend that you stick to the LOW END of the battery scale, that is the cheapest batteries with the lowest CCA in that size group. For some reason, I have always had better luck with these, they way outlast the high end batteries with tons of CCAs. I’m not sure why, but I suspect that they have fewer plates in them, thus the lower CCAs but the plates are thicker so they last longer.
I think you can find a solar battery charger that sits on the dash and plugs into your power adapter (cigarette lighter) to maintain your battery and that should also add years to the life of your battery.