Some people want to hear that yes, you can pull a 30' airstream with a mini cooper and I'll bet you can find someone on the internet who swears he has done it (or knows a guy who knows a guy who's done it. )
I saw a dodge minivan pulling a 24' airstream today on I25. They were going maybe 50 on level ground. I could not believe it. We went to a 98 12v dodge when we bought the 24' trailer. It weighed right at 6K. As has been said travel trailers are a brick. 8K of trailer with a car on it did not feel near as bad as my 6K brick. In the end speed is the enemy. @ 65 I got 17 go to 72-75 and it dropped to 11.