I intend to build a "spark plug" type lighting arrestor.

These are available commercially. I have one but have not installed it.
Part of the difficulty is the voltage at which they fire! Imagine what
it could do to tuner and possibly transceiver. Best to ground the
antenna directly outside the shack when it is not in use and hope!

Ed, N5EI
Thanks,

de ka2pbt

The use of a Balun, whether in the tuner or not, will allow your twinlead to
actually be at DC ground.