Thanks to all for your helpful information on this topic. And thanks
also for the notes on proximity of the operator to the antenna. This
is also of a concern to me, but it's a different question so I didn't
mention it in my original post.

The fact is, I'd be doing about 98 percent listening and 2 percent
talking anyway, and so I'm currently somewhat more concerned about
damage to equipment than damage to my brain which is already fairly
damaged anyway according to my XYL... ;-)

As for opening up the 706 to transmit out-of-band, this rig has that
mod (for MARS). If I didn't already have the integrated CB in the
Gold Wing I might consider using the 706 on CB and take my chances on
getting caught, but since the legal radio is already there, may as
well use it.