This is a starting point based on the 100AH battery.
100AH * 12 volt * 0.85 inverter eff *1/1 days storage * 0.50 maximum discharge = 510 WH.
Or your inverter at full output for less then 1 hour. You will most likely draw less but this is worst case Without your other loads.
1 LED @ 0.1 amp for an hour adds 5.1 WH.
Loads for less then one hour; an example 2 amps for 15 minutes: 2 amps * 12 volts * 15 minutes/ 60 minutes per hour = 6 WH
You can estimate all your loads that way. Total them all up and work the first equation backwards to get battery bank size; Or a quick and dirty estimate: total WH/12 volts
