I am not familiar with the Aprilia Mojito 125, but I wouldn't do it. I would not tow any bike that way, other than a chain driven bike with the chain removed. Even a chain drive bike (with the chain on it) turns part of the transmission, and I wonder what would happen if you hit a bump and knocked it into gear? I suppose you could pull the clutch all the way in, and fasten it there somehow, but I still wouldn't do it. There are hitch receivers for smaller bikes (I used to have one that fit my F150, so I could haul my dirt bike with the camper shell on it) and for bigger bikes, I would just use a flatbed trailer, load the bike on it, and tie it down.
I won't spend more on a bike than I think it's worth, but if it's a good deal, I don't seem to have a problem buying bikes I don't need.
2002 Vulcan 750, 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped