Dallas may be south but it still gets cold.
I will caution that the electrical boxes in most RVs are a tad anemic when it comes to 1500 watt heaters.. I have smelled hot wire a few times and seen evidence when I broke down the quick box outlet and replaced it.
I also added some quality 15/20 amp outlets with 12 ga wire wrapped around a screw and tightened down tight.. No problems with those. I used a different color to set them off so they are easy to spot.
Now what type... All electric heaters. be they radiant, hot wire, ceramic oil filled or ____ are 100% efficient. Does not matter.. So I go small (Ceramic) for the most part.