Since you mentioned boon-docking, I guess it is safe to say you want your SOLAR for more than keeping your batteries charged, while in storage. Like most, they want the most bang for their SOLAR BUCK, QUALITY products and service. I would recommend starting out with a few SOLAR panels and a controller that will allow you to upgrade your system, by adding more SOLAR panels down the road if you decide you need more SOLAR power.
To keep your initial investment low and your ability to add to the system, take a look at the Renogy 200 watt Mono kit (see below). It comes with (2) 100 watt SOLAR panels and a 30Amp SOLAR charge controller, which will give you the opportunity of adding 1 or 2 more panels to the existing controller (400 watts max). For under $300.
Batteries, well you can add SOLAR first and keep your existing battery (if it is still good and holds a charge) until you save your $$$ to upgrade. Recommended would be a couple of 6 volt 225Ah batteries to start. There is a benefit of doing it this way, you will learn how to convert to the SOLAR RVing Lifestyle. Granted, the battery power that you have available, will be about 1/3 the power available from the (2) 6 volt batteries, but you will not kill 2 more expensive batteries, during the learning process. The transition takes a little work and coordination with everyone that is learning how to live the SOLAR RVing Lifestyle.
Good Luck, and when you have a little time, take a look at the "
RVing with SOLAR" community. There is a lot of good information about SOLAR, batteries and mounting information.
Don
My Registry
RVing with SOLAR