Terry, I am a liveaboard and a heavy user, 700 watts of solar and 5 batteries x 110amp, 12v fridge, laptops, monitor screen, led lighting, water pumps, dvd player, radio, macerator, oven, inverter x 2(600 watt and a 3kw), shower pump, webasto, mifi's, microwave, mobile phones, slow cooker, etc the list goes on, i have 5 batteries but only cheap ones, if i get 2 years out of them i will be happy,(they are a year old now) they cost £50 each and when i scrap them you get about £7.50 back per battery so 2 years costs about £215 which i am happy with, i barely put the engine on during the week in the summer and only an hour a day in the winter, my suggestion for you would be think about more batteries when its time to replace them, (dont add new ones to old), and more solar panels, i had 200watts of solar last year and never had enough power the upgrade of 500 watts more has made all the difference, i have used the slow cooker this summer for the first time using up the excess solar power. I did buy the outback controller which cost £450 which is brilliant. We do have a travelpower as well which obviously works well for a quick charge when using lots of power.
I cant recommend enough to buying a nasa 2 battery monitor as well that way you can always make sure you dont let your batteries drop below 12.2.
I would say i have gone from 3 hours a day of engine use to 1 hour in the winter and from 1 hour per day in the summer to almost zero.
Solar is definitely the way forward now the price has dropped.