Hi Boony
unfortunately no one make a teeth proof leader that isn't 3or4mm dia other than wire
There are a few things that are possible but joining the leader will always be bulkier than no join at all
I find compared to others in the crew I get the most spannoes, I do get bit off occaisionally when there are lots of fish going for the one bait but I get a lot more takes than the other guys.. for the risk the catches far outweigh the losses
if you're casting flashas or taipans I use about 300mm of 100lb jinkai to a 60-80lb crane swivel because thay are black, small and don't flash
with floating live baits I just run 1200mm leader right to the top hook, trolling livies I do the same
when trolling bunnies tailor or big sea gar I tie the leader directly to the jig head
trolling lures and small baits like pillies is just about the only time I use wire these days and it is usually 1200mm 80lb single strand piano wire
I know it's not answering your question properly but it's all I got
thanks for the pics
cheers