The internet is the best. I found a nice write-up on crossbow trigger design that I'm going to try to follow:
The article details nut and trigger alignment, nut and stock alignment, etc. Amazing how minor differences in angles and pivot locations drastically change the function of the trigger.
Here is my first stab at the trigger, side view. The main issue I see is how I will re-cock the trigger. On a normal crossbow, the string moves out of the way so you can reset the trigger, on Stickvise the trigger gets blocked by the movable jaw after firing. Hmm...