Having recently finished a month on the road in winter conditions, I would go with a couple 170 watt Go Power or similar solar panels for a total of 340 watts with an MPPT controller. I would also have 300 AH of batteries or the most you can fit. I have 210 AH of AGM batteries effectively 105 AH battery power. Not enough for running the furnace, laptop, lighting, printer, inverter, water pump, phone charging, and other intermittent uses. The 4 gauge wire off the alternator never charges higher than about 13.7 volts. The solar charges to 14.5-6 volts on a sunny day. A lithium battery will give you better performance, more AH in a given space. Whichever battery you choose, 200 AH of usable power is the target at least for my use. I have seen the cost calculated between lithium vs AGM, lead acid and in the long run, the lithium costs less. It's that big up front cost you have to get passed.
