Once I identified one or two friends that had multiple adult male gypsies in their manors, I would go to their manor, trade with the guy as many times as I could, leave, and go back to repeat. After doing that several times, collecting horses and other items, experience points, and coins each time, I found that I could not only level up when I had no other way to do so at the time (without spending money or time gathering new friends to gain diamonds), but I could recharge that collection a few times so that I could keep doing that.
I have discovered that in the process of trading with these gypsy guys that I will collect enough horses to charge the collection yet again and get even more silver horse shoes, so that I can keep going back an infinite amount of times to trade with them. You just have to find a friend that has several of them in their manor, and once you've traded with all of them, leave and come back to do it again. It's time consuming but it is a way to keep playing productively while you wait for your stats to recharge.
FYI: I leveled up twice in less than 24 hours doing that.