There are lots of threads on the subject.
Here's a few:
http://www.alfabb.com/bb/forums/spider-1966-up/371866-towing-spider-700-miles-rear-wheels-down.html
http://www.alfabb.com/bb/forums/spider-1966-up/194988-spider-towing-dolly.html
I used trailer both times. Rental was cheap and gave me confidence that nothing would go wrong.
Good luck,
Vin