Sounds good but... the battery charge indicator on the tank level monitor panel that uses 4 LEDs to indicate battery charge level isn't worth it's weight in organic fertilizer. It will indicate fully charged when you are only close to fully charged. It takes 12-24 hours to really fully charge lead acid batteries and partial charging is quite harmful to them. your best intensions will only lead to a shortened life and all the effort to do the right thing will be for nothing. And, if they are wet or flooded cell batteries (they have caps to add distilled water) you need to check the electrolyte level monthly also.
It's not good to leave the batteries to their own devices as they will lose about 30% of their power monthly without being connected to anything (battery disconnect enabled). Of all the research that I've been doing regarding batteries, the only good solution is to either keep them on shore power or remove the batteries and place them on a quality multi-stage charger. If not, the partial charging will only help the sulfation process and slowly reduce battery capacity over time. They will become noticeably weaker each season, even though they are fully charged.
The only way to see if the batteries are fully charged is through a battery monitor system that uses a shunt to sense any and all current going into and out from the batteries or use a battery hydrometer which is probably not practical. When the charge current goes to zero, the batteries can be considered fully charged. Unless you are prepared to run your generator or engine for 24 hours every few weeks which is a huge waste and I don't recommend it, you don't have much else to chose from... solar?