A female acquaintance of mine in her early 80's just returned from a trip touring solo starting on the west coast going south, then east to Florida, then north to Boston, then west back home. She visited numerous national & state parks, and old friends along the way, going full circle around the country in her Phoenix Cruiser 2350 Sprinter chassis which is 24 feet long.
Hopefully your female friend will get over her fears of traveling solo. Just take common sense precautions and travel with a cell phone with internet and texting.