Are you going to do Osgiliath then? Since directly opposite Minas Tirith, although some several miles, is Minas Morgul, nestled in to the mountain wall of Mordor to the east.
And in between them, smack bang in the middle is Osgiliath on the river.
The only entrances to Mordor from Gondor is either through the black gate, which is much further north-east from Gondor, out of sight, or you can sneak in over the mountains around Minas Morgul.
Here's a little key which I've made.

Allow me to explain.
Hobbiton is done, so the next one is Minas tirith, once I have finished that, if there's enough bricks then I will do Helms deep, if not then I will make mordor out of mod terrain.
If I chose to make helms deep, on compleating it I will create the Black gate if there is enough bricks, Then Osgiliath if there's enough bricks, then Rivendel if theres enough bricks.
This is only a plan if by some miracle the brickcount isnt extreme after Minas Tirith.
I think what will happen is I'll finish Minas Tirith, Helms deep and I will have a mod terrain mordor in the background.