According to Tow Car Awards the Guiletta is actually a very good tow car up to 1,400KG
Alfa Romeo Giulietta | Tow Car Awards
The Mito seems to be rated differently for Diesel & Petrol
But if you use the 85% 'rule' 970KG would be its capacity.
I haven't actually towed with the Mito but I used to tow my heavyish 4.7m Rib with a BMW 1 Series which is about 200KG heavier than the Mito and that was rock solid at above the legal limithttp://www.rib.net/forum/images/smilies/hide.gif