Try U-Haul or JC Whitney forpower converters and harnesses...if you call them. Make sure you talk to somebody familiar with wiring Civics. There is also www.usa-trailer-hitches.com. They should be able to set you up with whatever you need.

I've now seen those tiny "smart cars" with trailers, FWIW. I don't think any of them were receivers though. Receivers are so much more useful...for things like bikeracks.