Ron Natalie wrote:
Indeed. However, the required safety pilot need not be the CFI,
and you could still teach a student under the hood -- legally
and without a medical, with a properly rated safety pilot on
the right seat (in which case you have three people on board
who can log PIC time simultaneously! :-)

One problem would be that the rules imply that the CFI and the safety
pilot both be positioned at the appropriate dual controls...

which rule? there is no rule that says the CFI needs to have
his/her own set of controls explicitely. Part 61.167(b)(4) which
does indeed say something like that explicitely only concerns
ATPs providing instructions, not CFIs -- now you could argue that
my proposition goes against 61.195(g)(2) but then I would argue
back that this clause concerns training for a pilot certificate or
rating and thus would not concern recurrent training of an already
rated pilot; now you could re-argue that 91.109 does mention
dual controls but then I would object that it does not say that
the CFI has to be seating at the second set of controls.

Now you could probably say rightfully that I am spending way too
much time reading the regulations and splitting hair, but I am
trying to prepare for an upcoming checkride :-))

--Sylvain