The minimum would be 160 watts if you are conservative with your power usage and are in a decent sun exposure area, 200 watts would be better yet. I have a 100 watt folding panel set that I bought when I had my smaller camper. Think of a battery bank like a bank account, you have to put back in what you spend or there will be a penalty.
(that being dead batteries, cold and darkness!)
There are a lot of considerations: where do you camp? East coast in the forests? portable panels are a plus, however being portable they do have the potential to grow legs and wander off. If you camp in open spaces the roof top are the way to go. Set and forget. My long term plan is a combination of roof top and portable for when we are under the trees.
With solar more watts is usually better, but they cost more. Wiring size and distance is critical, and you need a way to monitor what you are putting in and taking out, Trimetric
are both good choices, then you have to decide on a controller for the panels.
Determine how much power you would possibly use in a single day, then allow for a few cloudy/rainy days. Size your system accordingly. Many people find out that a small inverter generator is cheaper and easier in the long run.