From Utah
Here is basic primer on the RV electrical basics:
https://rvshare.com/blog/rv-electrical/
Our Cougar came with the basic "solar prep" package. That was basically a Zamp plug on the outside of the trailer wired directly to the batteries. I'm guessing your Cougar is similarly equipped.
2017/2018 units were not normally equipped with solar panels on the roof. That came later with the use of 12 volt refrigerators.
The easiest and most cost effective way to add solar in this case is with a portable "suitcase" kit. We added a Zamp 200w kit years ago and really haven't needed the generator since. This type of installation will provide enough power to keep your batteries topped off each day. Look at Zamp, Renogy or other manufacturers for a kit around 200 watts. These will include the panels, controller, stand brackets and wiring to the port on the trailer.
It's important that you have good batteries for boondocking or dry camping without hook ups. I'd recommend upgrading to 2, 6 volt batteries for the best off grid experience.
In this configuration you basically have a solar powered battery charger.
If you want to run any 110vac accessories like the TV you'll need to install an inverter. We wanted to watch movies on the TV so I installed a small 750 watt inverter in the entertainment center that allows us to watch movies and charge the phones. You won't be able to run the A/C, M/W or other high watt appliances like the wife's hairdryer
You can install more panels, larger controllers and inverters and battery banks if you decide your camping needs dictate that kind of set up. We've been very happy camping with the system we have mostly dry camping in National parks, State Parks and Dispersed camping areas.
Best of luck with your new Cougar. Have fun and be safe