I don't see how this would be possible even if you didn't care about the well-being of the finer materials that make up your interior surfaces. The other day I was attempting to crap a Thule Force XT XL cargo bin into the back hatch of my car and was probably two feet from being able to get it fully inside to close the hatch. That cargo bin is will under half the length you're talking about. I wouldn't even attempt something like that. If you don't have too many to haul a roof rack could be an option but safety becomes an issue and that's if you can even stay under the 150lbs or so they're rated at.
You can rent a truck from some of the big box home stores for $20/hr. I'd probably consider this if you don't know anyone with a truck. See if they have a long bed but even then those suckers are going to hang way, way, WAY out of the back. Flags will be mandatory and I'd say that even then it's a safety concern and may violate local laws of how far past your vehicle they can hang.
Best answer, find a trailer. I'm sure someone on Craigslist would transport them for you inexpensively.
