You certainly don't need to start over. You have some VERY nice (and expensive)renewable energy components there. Don't get rid of anything. You are heading in the right direction. Later, when you can remove some trees/branches you can add solar panels and have a nice system. You clearly are no dummy. You've done plumming and house wiring, so you will figure this out- just be patient and take the time to know (read the manuals, find out the info, etc.) what you are doing.
Probably the easiest method for you right NOW is to do what Kirt said and use the 120vac Charger that is in your Inverter to charge your batteries fully. The manual should show you how to hook the 120vac wiring into it from your Diesel generator. BTW, that inverter you have IS cabable of 220vac, but I would only do 220vac (high watt appliances) directly from the big Diesel generator myself. The power avaliable in batteries is limited. While you are using the Diesel geneator for other big things, it can also be charging your batteries, and when they are full it will go off automatically and a led light should come on. YOu already have everything you need to set this method up.
Or, You may choose the other method but it alittle more difficult. It sure sounds like that Windblue generator could be putting out about 20amps. If it is, then that would be around 1000-1200 watts of power going into the batteries @48v. You would therefore need a dumpload of 1000-1200 watts. It does not HAVE to be water heating elements, you can also go with AIR heating elements/or power resisters if you don't want to buy a hot water tank or don't have the room for one. I thought you said you have a propane heating tank anyway.
If you get that new Diversion Load controller, you should probably make sure it has an Ammeter on it. (sometimes it is an optional lcd screen)
Read the manual thru and set it up for your 48v batt system,(it probably has dip switches inside) and hook the 1000w water/air heating elements up to it,(as the manual says) and the charger will automatically charge the batteries fully and a led light will come on when they are full.
It would be a good idea that if and when those batteries go bad, that you DON't replace them with the same type of battery. Instead, get some T-105 TRUE deep-cycle batteries or similar. (Golf cart batteries are good and economical too. They may last half as long as t-105's BUT they cost half as much. About the same I think)
Sorry I can't help more, but I am more of a beginner like you. Never get discouraged. You'll get it. Just keep studiing here and asking more questions!
P.S. You might get some more 'extra' help and pointers from others if you could give Your email address. Worth a try perhaps.