The connector is same as Zamp, or is a Zamp connector. It is also known as an SAE connector. Used in many applications, automotive, sound, solar(!), etc. The plug with a pigtail on it, can be found almost anywhere!! Many wire gauges also avail.
Here is a plug sample: Quick Disconnect Wire Harness 2 Pin SAE Connector 12 Gauge PC120 | eBay
Zamp and some other portable solar panel setups use this connection. Can just place panel in best location, and plug in!! Most portable systems over 10 or 15 watts should have a controller attached or incorporated into the setup. The plug on the trailer probably goes directly to battery, so anything 10 watts or lower could be directly connected. Over 10 need a controller!! Keystone may be able to pdf a wiring diagram for your trailer model so you can find out how the plug is wired.
If you do your own connection for a panel or (?), double check the polarity carefully. Easy to flip the connections along the way, esp when using only a single plug and wire vs a cut apart loop style.