question

If you don't plan on adding any panels in the future, I'd go with SmartSolar MPPT 100/20. If you add more, look at the 100/30 or 100/50.

As for keeping your batteries topped off, I have 400ah of lithium with only 300w of solar. My electrical needs are high (cooking with induction, electric kettle and microwave) and I find that 300w keeps me charged up for the most part. Those loads are for short bursts though so you may have different requirements. You may also live in an area with lots of cloud coverage (I'm in Nevada so I get plenty).

Kieron, I have a motorhome and use it a lot off grid. I recently upgraded to a LiFePo 110Ah battery from an AGM. You get almost double the useable power from LiFePo vs lead acid and the charge rate can be much higher. Before spending on a large battery bank, be sure it has enough useable power. Total power will get you through cloudy days and charge current will help top up faster when solar energy is available.

We seldom drop below 75% charge on a 3 night stop using a domestic coffee machine via inverter, all lights an tv for an hour or so. The fridge is on gas.

In the winter there is a danger of running low though.

Take inventory of your power needs, mainly what's consumed during the day. That will give you an idea of how much battery and solar you need. There is a handy solar calculator here that will help with sizing your solar system:

https://mppt.victronenergy.com/?locale=en

The calculator will even recommend a solar controller.

Series vs parallel choices are well covered many places. I found series connection of my 4 100watt panels gave me the most output in partially shaded conditions but your milage may vary. I recommend designing the system with the ability to change series/parallel wiring and running your own tests.

Have fun.