Awf Hand from Chippewa Falls, WI on 5/15/2015 3:42:30 PM:
Trailers add another element to bike-packing and have many benefits/detriments.
You'll be adding weight. Trailers weigh about as much as 1/2 bike, easily, and the only thing they are really good for is hauling your stuff. They require some sort of coupler to connect to the bike and can change handling by causing "fishtailing". They also require a prudent traveler to carry a spare tube in case you have an issue with the tire, the size of which doesn't match your bike. Also, if they break down, you have to figure out how to move the trailer and gear to a place you can be picked up or repaired. You also have to transport the trailer to your drop-off point from your house and they don't always fit well on bike racks.
Benefits include, easy to put on a bike with no rack bosses, allows the tow bike to use lighter rims and you can take way more stuff than you'll probably need. They are pretty durable and I've seldom had handling issues. I rode the Katy last September with my 9yr old on a tandem with (2 wheel) trailer. We were able to use the trailer as a food prep/dining surface and as a cover over some of our gear that we wanted to keep dry during the rain. This particular trailer was a converted Burley kid-hauler that connects to the left chainstay with a clamp. It worked well and we couldn't have hauled all of our gear on the bike alone.
If I was traveling alone, I'd keep my gear on the bike and use racks/panniers regardless of how long the trip was. Travelling with another rider who may not be as strong, I'd happily pull a trailer.
From what I've heard, the 1 wheelers (BoB or similar) are best for the C&O. You have to determine if what you're bringing warrants purchase and towing of another "1/2 bike".
For a solo rider, I'd say no.