The towing eye is a triangular sheet of metal, depending upon year of construction, screwed or riveted into the body. Altogether one should be careful with all vehicles towing, this construction seems particularly flimsy. I however still know from no case at which the towing eye is torn off..
If El is towed because the belt wore out or tore, one should fix these beforehand in such a way that the drive can turn freely. If the belt is already strongly damaged, I recommend to cut through and remove this with a side cutter.
Towing one el with another is possible, although with restrictions. One fastens the rope to the left end of the transverse stabilizer as the left wheel only is directly propelled. With tight curves it can be that the rope at the rear wheel scrubs - caution.
On the level towing another el is no problem, at mountains is it however quite consumptive of battery charge.