Portable might be a long wire back to the RV. You might do well with a 24 volt panel in 200 to 270 watt range and a small MPPT controller. Large panel might be awkward at times but at least it is only one. With higher voltage your % losses in the wire will be cut about in half as compared to the same wattage through the same wire.
If you might mount a panel on the roof (I recommend this) consider a 30 amp Morningstar MPPT. The portable can be used in parallel with the fixed roof mounted panel.
Lots of ways to implement solar, this is just my random thought of the day.
Morningstar 15a MPPT 1 panel $240Morningstar 30 amp 2 panels MPPT $335