Sounds like a good plan. We have the solar boost 2000 and started with 2 K120's. You can add a 3rd pannel later on if desired.
4 golf cart size batteries (T-105 or similar) is a pretty standard setup. That's what we have. We use a lot of power, and don't have any reserve when dry camping. So if it's a cloudy day we have to run the genny.
Getting a good high amp charger (as you'll have in those inverter/chargers) is also a good idea. No sense in wasting time and fuel running the generator and charging batteries at a slower than optimal rate.
Here's a link to some solar and RV electric info we have posted on our web site.
Mac