NA Miata - tightening the shaft nut on Koni Yellows, no flats, rattle gun or what?

I thought we had discussed this topic before but I couldn't find it with a brief search.

Anyway, I'm assembling my new Konis + springs with new top mounts and have run into the problem pretty much everybody seem to hit - how to tighten the shaft nut "enough". The nuts are on and the struts are assembled, it's just a matter of making sure the nut is tight enough. You're not supposed to tighten them very much anyway (IIRC around 10lb/ft) to avoid crushing the hollow shaft, but the shaft starts turning well before I get to that level of torque.

Attempts at gripping the shaft in such a way that it doesn't damage the shaft have failed so far. Basically the suggestions seem to be to use a piece of thick enough rubber or old heater hose with pliers to hold the shaft without damaging it.

The other option that seems to be mentioned in several places it to hit the shaft nut with a rattle gun with the torque turned down, or use a nyloc nut. Of course the problem with a Nyloc nut is that they require a little more torque in the first place just to tighten. 

The shaft doesn't have the usual flats that allow one to use a second wrench to hold the shaft (for those not familiar with these specific Konis). 

I'm tempted to try the rattle gun method, what's people experience with it?

And yes, I realise I could ask tech support at the vendor, but I can't do that until Monday...

I wrap the shaft tightly in electrical tape -- 7-8 layers thick.  Then I put the vise grips to it and hit the nut with the impact.  Remove the electrical tape and any adhesive....no marks.

(Don't tell anyone my secret, because it's the wrong way to do it. )

In reply to BoxheadTim :

I used my HF battery impact. I did it with the shock in the vice & the coil perch dropped so there was no tension on the spring. You can’t get the nut very tight before the whole thing starts spinning anyway. I took no steps to be gentle however. 

As an aside - be careful undoing the nuts with an impact. Spinning the rod too much in reverse can back off the internal nut/piston inside he shock.