Originally posted by GunsForBucks:

You can place a wooden beam normal or log sticking out half way.
That way you can walk out "in front" of the extended part to place new ones, once you have one in place you can snap the row to the side of the first one.

Damn!

It is so simple that I am almost shocked that I didn't though about it earlier. It cannot try it right now, but it should work perfectly.

Thanks!