OK. here's the idea. Permanent wormholes.

Instead of those tiny sub-wormholes (that you need the survey ship to use), how about wormholes that you can use to teleport your ships from one end of the wormhole, to the other!  ! Of course... each ship would need a special module to allow it to move through the wormhole, and I also think going through the wormhole should take one week, as to restrict it a little bit.

So, what do you think?