We live onboard permanently in the South of France in a single engined 42 ft fly cruiser where it can get up to 45 degrees celsius in the summer.
I don't mean to be rude but why are you guys so pampered with electric stoves, microwave, AC units ? Why have AC units and then go outside and lie sunbathing ? You don't need all those heavy load acoutrements, never mind all the extra cost/maintainence issues.
Change to propane for cooking, plan your meals in advance ditch the microwave.
AC units ? Get out of the sun ! use neatly shaped clean white sheets cut and shaped to cover your boat so that a, its in shadow and b, open windows capture any cooling wind and c, the wind chill effect cools your boat.
Fit 2 alternators and control them with battery management system like the ADVERC alternator controllers for maximum efficiancy charging. We have 1,000 amps domestic battery bank and 300 amp separate starter/bow thruster batteries.
Our hot water comes from the engine to a heavily insulated tank fitted with a 1kw immersion for shore power and and a mixer valve to regulate (and save) hot water and that lasts us for 2 days hot water/showers or 1 bath. We make sure the boat is securely attached, start the engine and put it in gear in its 'sweet spot' around 1,000 revs every third day for about 45 minutes to reheat the water and charge the batteries. Fridge and freezer have auto change 12/220. We have an 3 kw inverter to drive the washing machine/dishwasher which is only used when when cruising so it floats the load from the alternators without reducing the charging rate. Because the Golf Du Lion is very temperamental we don't anchor out at night. When at sea cruising we're recharging the batteries and getting cooling wind, when in the canals we moor under trees for the shade.
We have 1 350w solar panel which helps the batteries run the water pump and fridge/freezer and give us up to 3 days autonomous mooring by then the admiral (who's French) will be looking for fresh baguettes and either fish, mussels or fresh oysters.
If your an eco warrior or need to be careful with your money, instead of using diesel use HVO (Bio diesel) and cut your emissions by 92%
if you can get it. It's a direct replacement for diesel, no mods to the engine are needed, it's diesel bug resistant and stays fluid down to minus 20 degrees Celsius.
We just have a different approach to stress free life I guess but it seems to work fine for us.