I run single siwash on most of my kwikies, whether I have to or not. While I haven't had to use just one hook, I seem to recall most of our fish being hooked with the belly hook rather than the tail hook.

I rig them by opening the screw eye, adding a 120 lb test swivel, and then closing the screw eye. Then I add a siwash, size 3/0 for a k14 to a 5/0 for a size 16.

I find that once the hook is in, they tend to stay hooked. I think we typically hook about 70% of the strikes, and we land about 80% of those fish that are hooked. I haven't been able to tell any difference between trebles and siwash in hooking efficiency, but have not kept detailed records. I have at least an emotional belief that the siwashes hold better during the fight, and they don't seem to get mangled like the trebles do.

If I were force to use one hook, I'd use a swivel or short bead chain, and rig the belly hook. I'd also downsize the size of the lure to something that was more likely to put the hook into the mouth of the fish, like a k13 or 14, rather than a 15 or 16.