Here is a link to a number of teardrop designs that would be cool to have behind the Model A. I purchased the plans for a "Chummy" which is specifically designed for the A. You might consider contacting the designer for more details on towing with your Ford. He has a lot of experience.
The only problem I had was with my insurance company (Hagerty) who would not insure my Model A with any trailer behind it. I switched to State Farm (more money) and I was covered.
Gar Williams
http://www.teardrops.net/plans01.html