I wish i could give you some useful advise. but i dont really have any.

have you thought about using prong collars?
ive heard good things about them,, but havent tried them myself or know anyone who has.

i found a couple of websites that spread good light about them though..

http://www.oaktrees.org/henrey.shtml

http://www.cobankopegi.com/prong.html

http://www.flyingdogpress.com/prong.html

do a yahoo or google search on them. there are tons of websites out there with pictures and info.