Not strong enough. Those threads are made for limited emergency use.
You will want a blue Ox set up or simmilar. Plenty have been done in the past and the shops should have good experience by now.
Spend some time in the Towing section of the site
Smart Car Towing - Smart Car of America Forums
Oh, and welcome to the site. Your going to love taking the smart on those day trips while leaving the home parked. Even the smallest quaint tourist towns full of people will revel a prime parking spot just for you.