Well then, it's easy: Just always face the exhaust in that direction! It's not rocket science!

What if the front one is only a small fraction of the thrust at the rear? Would that be enough to "clear the path". Surely it would cost some efficiency but it may beat he alternative

In other words the space-equivalent of a supercavitating torpedo like the Shkval [1], more or less an underwater rocket which creates its own gas bubble around the projectile by deflecting part of the exhaust stream to nozzles on the front of the device.

[1] https://en.wikipedia.org/wiki/VA-111_Shkval

Whipple shields [1] don't weigh much, and don't involve negative acceleration of any kind.

1: https://en.wikipedia.org/wiki/Whipple_shield

In a universe where every action has an equal and opposite reaction, why not make those reactions argue about it?

what about for the period of time that you're travelling sideways with a largely unshielded broadside facing not exactly empty space?

You wouldn't literally turn around.

You'd probably move your rocket engine over to the other side (or have both a front and back engine in the first place).

Most of the mass of your spaceship will be fuel (like 90%+). You can use that as shielding.