The spring could fit behind the spike the latch threaded to fit in the spike to make assembly easy.
Sounds like you'd be making a spring assisted gate latch with a sharp point.
Got it, that would work for spring being same OD as Spike. 5/16 or 3/8 spring and spike. Maybe 3/8" provide more meat for side hole threads for lever.
I was thinking of Compression spring with ID a little larger then OD of Spike and put it in front. This way the spring is forcing the spike to a safe position, vs other way around.
As I'm just thinking, This would get rid of retracted side slot. Say spring is holding spike in with 1 lb. Then diver cocks it forward and latches it so Spring is at 3 lbs, then rotated into slot for Danger position.
Back side of Housing will need a threaded Cover, and a Lip on the Spike on back side for Spring catch to spike. The spring can be referenced off the lever too.
Another feature, might not be way to go, but still doable. Going to need additional holes for rinsing salt out of it.
Hope my rambling makes sense. A picture would be easier, but George Kill me, suppose to drawing on his Slip tip