Playing with 43 civs changes the game drastically.Here it is Minh. What I am talking about. 3 vassals on deity in mid-Renaissance.
I haven't revealed much of the world (supply cap is so severa than can't spend on a scout even) but this is 43 Civ game. The stats may not be that impressive to nerds like you on first sight but the important thing to remember is that I am surrounded by vassals. My army is now free to roam and harass the leaders. Nobody can pose direct threat to me anymore, my vassals are protecting me and all of them are very happy with me. Yes the leaders are about 300-400 points ahead of me but mostly because they have wonders.
My biggest issue at this point is supply cap. To solve this problem I will annex capitals from now on. There is no point, I think, to make more vassals than this. It is mid-game and I have to choose a victory condition. So far it is Authority-Artistry and I have to pick the third policy. Still considering what that should be.
You have not won. You aren't the score leader. Are you the science or culture leader? What makes you think this strategy is good? You haven't revealed the world at all and Can you take that 5 city empire all the way to a victory? Show us. I think there will be a snowballing civ far away from you, and your position makes it so hard to deal with.