Buy a roll of 18 gauge rebar tie wire. A lot cheaper than chain and you can easily adjust to the length you need at the set. I, generally, use two strands of wire. That stuff is super flexible and takes a lot to break it.
Do you have otter? I don't think that would end well with otters. We have them everywhere here so chain and swivels is what works for us.
While otters and coon are not the target species, I had no trouble holding either species. I did have a few pull the stakes and tangle up nearby. I was running 200 traps on marsh/Missouri River. Again, I am setting fast and frequent, primarily on rat huts and feed beds. If I had been running sets that would have a higher percentage of non-targets like otter or coon, yeah, I would manage things differently. The key to holding non-targets at rat/mink sets with wire is to not allow that animal access to land where it can tangle the chain or wire on something solid and pull out or cause harm to itself. I have taken thousands of rats and hundreds of mink this way, not to mention quite a few coon and 3 otters that were released, unharmed. It is the ONLY time I use wire to secure traps. Never on land or for target species larger than mink.