We do not know the health of the Op's battery, and flooded batteries can self discharge 15% a month at 75f. The less healthy the battery the higher the self discharge.
We do not know the parasitic drains on the Op's vehicle, and how much of the batteries capacity is remaining, so the question is unanswerable.
Fully charged resting voltage varies battery to battery so the 12.8 or 12.6 absolutes one hears time and again do not apply to every battery across the board. AGM's can be have fully charged resting voltages over 13v while some healthy flooded batteries are fully charged and resting at 12.6v.
Without knowing the specific brand battery in the OP's vehicle, voltage absolutes as to state of charge are not applicable.
Float/ maintenance and trickle chargers vary widely in effectiveness, voltage setpoints maximum amperage and capabilities. Since we have no Idea what charging source the OP has access to, any recommendations are rendered moot.
In general the higher state of charge the battery is kept at, the longer it will last. You can trust your charging source and all the marketers claims, but there is only one polygraph as to how any charging source is fairing on a flooded battery, and that is Hydrometer. A glass turkey baster style hydrometer with a glass float and with a means to adjust SG readings for electrolyte temperature. If you have a plastic hydrometer which claims to be temperature compensated, give it to your enemy.
If you have a cheapo hydrometer with the floating balls, then give up all hope of knowing what is going on with your battery for ever after and hope the prorated warranty can be applied when necessary.