Excellent work Romir.
It all ways the way, it's the last one that you need to do that either cuts you or it not until the last one you pick that you find the one you have been looing for.

As you havn't layed any pipe yet and there is still time.
I would think now is an Excellent time to up-grade to the 100' roll of 3/4 pipe.
For $30 bucks it's not worth kicking your self later once it's all buried in the ground, with the, would of, could of, should of, If only!!!
Do it NOW!!!!

Plus a bit like what Serialk11r said.
You could also easily lay two or three full length runs on top of each other with say 8-12" of dirt between them in layers in the same trench.

What do you think???