As Lifeline says batteries are 'the heart of your system'. It's not simply the size of your battery bank that matters when you add solar, it's the type of battery.
Given the latest tech on battery development, liquid cells are now at the bottom of the pile. They require constant maintenance, produce flammable and corrosive gasses when charging and have very high internal resistance which requires a higher level of charging amps to get them to capacity.
AGMs require no maintenance and with a far lower internal resistance, can be charged at a much more rapid rate than liquid cells given the same amount of charge capacity. There is also no danger of gassing or the associated corrosive effects with AGM batteries when they are properly charged.
Lithiums are the best solution presently available, as they produce far more usable amp/hours per pound, do not produce gassing of any type so they can (and should) be placed inside the RV and due to their extremely low internal resistance, can be charged extremely fast. The ARE expensive and require external battery monitor systems to properly control the charging.
Once you decide on the size and type of batteries that you will be using in your system, then you should start designing a solar array and associated charging system that will best compliment your chosen battery bank and your intended use of your rig. Proper battery charging is the foundation for long battery life, regardless of the type of battery that you select.