Hello moriador, thanks a lot for the work so far.
And all look very well made.

But question :
Why not stick with the default square surface?
Most 3D apps work best with square textures at 512x512 up to and often including 8192x8192 
For tiled textures?
I would opt for 512x512, 1024x1024.

Even 2048x2048 is on the big side tor tiled textures.
Just a thought.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!