If your faction is on defensive and destroying the offensive towers is your best interest, there is a way to avoid the main road or to avoid having to go to the southern tower (where defenders are sure to be waiting). Cast water walk on your siege vehicle and just drive on the water terrain and reach either the south east or south west towers directly.
For starters, grab a vehicle from your base, either east or west, then exit using the teleporter. Sneak to the main middle road and head down to the lake (east or west) and just bypass the main roads and go straight to the towers. Since the main roads are elevated (eg. the lake is low ground) find ways to get back to it to access your targets.
Im working on the screenshots, but this is self explanatory. Leviate not tested, Path of Frost did not work.
TLDR, cast waterwalk on vehicle and use a safer path.