I think the battery may not be enough to cover what you want to do.
I am building a 24 volt 12 kwh battery pack. I think I could run a mini split in the day, but not a hot water heater also.
I do not have a minisplit, but a future plan would be to add one to my fifth wheel, with close to 2000 watts of panels, about 700 more than I have now. I could run one AC, but not two AC. Those are the back of my napkin calculations, and if I choose to install a minisplit, it will be next year in 2022. For now, I have a standard RV 15k BTU AC and a 3000 watt inverter planned to be installed, and because of the huge draw of the mote on spin up, I expect it not to work on the current air-conditioning.
My hot water heater is 1500 watts and needs to run a long time to warm up. Propane is much quicker and efficient. I do expect that the larger size of my system compared to what I have now will now let me run hot water in the day on solar.
At 12 volt 2.6 kwh usable energy, I can watch all the TV I want, run my propane heater all I want without worrying about the 100 watt draw of the fan, brew all the K-Cup coffee in a 500 watt brewer the wife and I can drink, and run the microwave that draws 2100 watts for a couple minutes a time four to six times a day. With the 24 volt, 10 kw usable upgrade, I expect the same plus now we can use the microwave all we want. Not just to warm up food, but to cook frozen dinners. Once I see how much power it has, I may run the 300 watt fridge off electricity most of the time, which is actually a huge draw on the long winter days where that's a lot of electricity at night. I think I may try the hot water heater once in a while and see how that goes. If the fridge and water heater work fairly well, that's when I start the mini-split conversion.
