Lil Snoozy's factory is in SC and would be a good one for you to consider.
Scamp and
Casita are also good choices. If you can get inside of each one, you will have a chance to evaluate how the floor plans feel to you.
You are wise to be looking at trailers with rounded edges and corners like the molded
fiberglass. They will tow easier behind a Highlander than a boxy trailer could, meaning better mpg and less strain on everything.