Imo the poly count is fine, in Medieval Total War 2 this range is used for lod3 models (i.e. the 4th stage, lod0 is around 3600 tris), but that game is heavily optimized for RTS (instancing, pathfinding, group movement, collision). Earlier in Rome Total War the poly count range was about 650 for lod0 and 225 for lod3 models. And they are still not bad if don’t go too close with the camera 
MTW2 used 26 bones per human character, RTW had an additional 1-2 for cloak. (Do not speak about Age of Mythology, those stylized models were extremely low poly, but after conversion I really enjoyed to see how well they were designed…)
Moreover, TW games used animated sprites for far units, what I also found a good performance friendly solution in my RTS prototype (made with another engine, under porting to UE4) despite the transition is visible because they are unlit.
I would be interested in the benchmark results if once you complete it. (I have a slow notebook GPU, but 400 characters taken from RTW can be represented with acceptable performance beside a simple movement behaviour in a simple landscape populated with instanced trees.)