I'm kind of trying to transition back to more semi-normal work but have been known to pull a trailer from time to time. I usually set a per mile rate based on the type of trailer. Rate usually varies directly with the expected gas mileage and age of the trailer. I normally quote for round trip mileage from my home in Wichita to the trailer to where the trailer is going back to my home. Uship.com and others (like Tim's guy) who are professional full time transport guys will quote you probably at a lower per mile rate and just one way.