Hi from San Diego
Welcome, Mark and Wendy!
The nice thing about molded fiberglass trailers is that, with patience, you can probably find one old enough to be well past the outgassing stage, but still in good condition. Then you can choose your own materials to update the interior.
Do you have an idea what sort of trailer will meet your needs- size, features, layout,...? Do you know what the manufacturer's tow rating is for your Explorer? Do you have previous RV experience?
Best wishes in your quest!