I was thinking the sander because of the risk of unfound metal in the
boards ruining planer blades. If I can only shave off 1/32 at the time
with the thickness sander, I should be able to catch any nails before
they damage the drum.

yeahbutt... you will have destoyed the knives in by then.

Please forgive a stupid question, but how does one damage the knives in a
_sander_?

OK... I misread it

Don't do it with a planer, don't do it with a sander, or don't do it at
all?


Go ahead and do it either way. Grit sand finish nails... they are all hard
on abrasives or knives and saw blades. either a huge amount of time will be
spent removing foreign material or their will be significant expense in
blades etc.

I've done it. It was particularly nail and sand ridden stuff, but it was
special wood.

-Steve