Richard,
If the feral callery pear situation is anything like it is here in NJ, I
suggest you just top work some feral ornamentals at about 4-5 feet high with
your scions and you will have instant deer proof trees. Deer won't touch
callery pear here, and we have A LOT of deer. I have been doing just that
for several years now and have several acres of semi wild pear orchard in
the making. I have gotten pear, asian pear, hawthorn, sorbopyrus, and even
apple to take on the caller pear using cleft graft, although I expect the
apple to abort.
justin west
NJ