Liz,
we use (in Queensland - out in the colonies!) a lambswool numnah - although it
larger than the normal dressage or all-purpose size- and under that we put a
pad of sheepskin. this with the wool down obviously. we've been using this
combination for the last couple of years with no problems, and many kilometres
to boot.
re body clip - we clip all over with the exception of the saddle area and the
legs. it does get pretty hot here i.e over 30 C, and we do clip our
competitive horses in winter as well - but we have the luxury of winters that
average daytime temps of 18-25 C.
We find that when the horse comes in at the end of a leg, too much hair retains
the heat.