YMMV and all the standard disclaimers:

Once again, the video instructions demonstrate their value.  Had TVM
not shown the specific technique for cutting out the vacuum-form wraps
at the antennas and such places, I'd have made a dog's lunch of the
job.

Not much to tell here.  The epoxy-microballoons mixture used on the
first-stage fairings was also used for the tunnel covers.

Special care should be taken to smooth out the epoxy on the smaller
tunnel cover, and to remove excess before it's cured.  That thing is
awfully difficult to hold in the fingers while sanding (for that
matter, the larger tunnel cover isn't too easy to hold either).  I
tried a Post-It note, stuck to the other side of the small tunnel
cover.  Held Post-It between thumb and finger, with other fingers on
the back of the Post-it, and not a whole lot of pressure.  It held
reasonably well while sanding.  If someone has a better idea for
holding little parts, please holler.

One minor addition on the tunnel covers:  I used a flat file to recess
the parts of the cover that fit over the 3rd stage wraps, just a
tenth-millimeter or so.  I also sanded the wraps a bit where the
tunnel covers go, to remove the slight ridge at the edge.  The tunnel
covers now fit tight against both the wrap and the airframe.  I guess
that's a little anal...

P'rfesser