aside from shading issues, which are indeed critical for some (not all) panels -check the bypass diodes configuration for ex to find out-, some points to consider are what the max voltage and current capabilities of your controller are (likely not a big issue if those are "12V" panels as I assume they would be) -but worth thinking about for later flexibility- and the size of the wiring if need to handle higher current in series (you may need bigger wires, fuses etc). Of course, you'll want to make sure that the controller can handle the 200W. For example, the Victron 75/15 which has been discussed a lot here, will be able to handle 75V in, fine for 2 (or 3) "12V" panels, but is limited to 15A output so about 220W with one 12V battery, so you would be close to maxing out the controller with 200W and would not be able to add usefully another panel later on with that controller and the one battery.
I don't know what a Redarc DC charger does, but I got an MPPT controller, not a PWM. More energy that way, but debatable whether that is worth the extra cost, especially since 200W on your roof is a lot for typical camping needs so you likely won't be hurting for power in the summer. (Are you sure you need 200W?) But also more forgiving (I think) of incoming voltage fluctuations due to insolation changes, shading etc.
There are also other issues relating to the controller, like the charging schemes (various phases), ability to set up custom settings, deal with various battery types, etc. The means of programmability of the controller are also important, like do you need a computer or a phone, etc?
The good thing is that if you get a reasonable charge controller and good wires you can go easily go from series to parallel and find out for yourself what works best for you. It's not like you are locked in forever in one mode. Very easy to do (and interesting for us nerdy types).