The best part of solar is that it continue to charge quietly when exposed to the sun.
If your RV spends more than 3-5 days not plugged into power, you will benefit from some type of solar.
It is a constant battle to keep your deep cycle battery charged as every RV that I have seen has some type of constant loads on it. It may be your refrigerator, propane sensor or a low voltage cut off switch. It is common for RV’s to have .5-2 Amp constant load. This equates to 12-48 Amp Hour-AH draw off your battery every day and this is without you using anything! You can find your actual load by using a clamp meter or a battery monitor. Many converter chargers only put out 13.6 volts and all batteries want around 14.4 volts to get charged. With enough solar panels and a good solar charger this can all be fixed.
A generator is a great way to bulk charge batteries, most converter chargers can use up to 850 watts for this process. When it comes to the 2-6 hour absorption stage the generator is very inefficient. A 220AH battery may only accept 150 watts during the majority of this process and the generator will be rated in watts as well. Many boondockers will run the generator in the morning to bulk charge and then let their solar panels finish the charge process. More on battery charging here.
I live in my RV on BLM ground most of the time and only plug in to shore power less than 12 days a year. I have roof mounted and ground panels. My roof panels provide all of my power requirements most of the time. I believe the ground panels are required especially in the winter when the day is much shorter. Solar panels will pay for themselves by not needing to run the generator.