I don't see why you can't do it as long as you don't go too crazy with the load on your car. But if you wish to just tow a bicycle or a motorbike or any other lightweight load you should be fine. I would first read the technical book and see if it is acceptable and also search on more information on different websites.

Here is a good resource for you to read more about towing guides:

www.batesontrailers.com/trailer-towing-guides/

Also about specifications, you can try www.pistonheads.com/gassing/topic.asp?h=0&f=10...6

I run a small removals company based in Bristol - Avon UK and I have seen some of my clients doing the same thing to carry some of their lightweight stuff when moving to a long distance and didn't fit in the removal van so that's the way to go.