Trying to stay with a single group 24 battery is tough.
Even with a single 100 watt panel being sufficient, a single day of rain eliminating the benefits renders your actions near useless.
To go frugal, and have meaningful benefits,,,
If you can, switch to a pair of GC-2 batteries and your single 100 watt panel. When you select the controller get at least a 30 amp unit, so you can add to the system as finances allow.
Your single group 24 only yields about 76 Amp hours of power.
Most sources say you should not routinely draw it past one quarter of that amount, one third at most,
so you have 25 amp hrs available normally before you start damaging your battery.
A pair of GC-2 batteries wired in series will give you a total of about 210 Amp hrs, of which 50% is usable with no damage to the batteries.
4 times the readily available power.
$180 for batteries in conjunction with a single 100 watt panel will give 4 times as much available power as you currently have, as well as the ability to regain much of that power by solar in a single day. You can hit a rainy day or two without running out of power at your old use rate.