You will need something to hold the body close to the valve..that is the rails secondary purpose.
you could figure out the right place for your pivots and use the wood stock to mount the trigger sear instead of mounting the trigger on a rail.
Like you said
There is a pin hole for the sear pivot
A Twist lock assembly if you use it
And the valve is held to the body via the rail.
"I'll see it when I believe it"