I always recommend starting with an energy audit and figuring out what your need will be 30 - 40 amp hours per day is pretty common. Decide on battery type.
If AGM (or any Lead Acid type) it is best not to routinely draw the battery bank down more than 50% and always fully recharge every day. That drives the charging system you need to cover partially cloudy days etc..
If lithium then you can draw it down to 20% or so (check manufacturer recommendations for the battery brand you select) and lithium does not need to be fully recharged everyday.
Now you know how much power you need from your charging system everyday.
I recommend putting the largest rigid single solar panel that will fit on your camper, even if it provides more power than you think you need. Preferably, get one around 320 W or larger. It will cost around $325 (maybe less on 2024 I have not checked recent prices). That panel will be lighter and cheaper than any combination of smaller rigid panels providing anything close to the same amount of power it will also maximize the ability of keeping your battery charged.
I still recommend avoiding flexible panels. The evidence still shows they have much shorter lives than rigid panels and they need to be mounted with a 1" air gap under them (between the top of the camper roof and the bottom of the panel) so they do not overheat. This is the same requirement for mounting a rigid panel. Also, the cost per watt for the semi flexible panel is more than that for a single large panel.
You will probably be glad you went with one large rigid panel later. Just look at all the threads about adding a second solar panel. That approach is more expensive and results in more weight. It often results in needing to upgrade the solar charger too.
While AGM or lead acid systems work well and can last 10 years or more if not routinely under or overcharged, I recommend lithium of you already have a solar charger and the DC-DC vehicle to battery charger which are needed for a lithium battery or if you just want to spend the $$$ and replace all of your charging electronics along with the battery(s). Otherwise, replacing the AGMs is still reasonable if you manage the charging and discharging. Also you do not need to worry about charging in cold weather (although that seems not to be much of an actual issue with lithium batteries in real world camper applications).
I hope this is helpful.
Craig