Why the extra trip? Many people inspect, purchase, and drive home on a single trip.
But perhaps your vehicle is not yet set up to tow...? If you a newbie to towing, know there is more to it than just trailer
weight and tow rating. Has your research gotten into things like tongue
weight and hitch rating, payload, trailer
brakes ...? Have you read the entire towing section of your owner's manual? You do seem like the thorough type!
Our 13'
Scamp was also a somewhat impulsive decision, and it did end up being just a bit much for our vehicle at the time, good on paper but not in the real world. In the end we got it sorted out, and the trailer has turned out to be one of the best purchases ever!
Your inspection should look for signs of water entry (windows and belly band are the common Trillium leak points). Ask when they were last resealed. Feel for softness in the floor. Trilliums have a layer of plywood sandwiched between
fiberglass. Not as common as
Boler and others, but there are ways water can get inside and rot the wood, resulting in a spongy feel. Check operation of the Bargman door latch. It's a non-standard, vintage component that's not easily replaced.
Welcome to the group, and best wishes with your trailer shopping!