I'm just going to lever this right here.

Here's my latest idea for my SCR trigger.  Instead of a big long extended trigger, it uses a short lever to transfer motion from the new trigger to the tail of the original one.  It uses a second AR trigger with the tail cut off, but it could probably be a printed part(I'll try it just to see).  The lever can be made from a chunk of 1/4" square stock, although it may be able to be printed too.  The original AR trigger needs some of the tail cut away for the lever but since there is no disconnector in the way that's not a problem.  Here you can see how everything sits in the cocked position:

In this system, the rear trigger only needs to move 5°-6°, pretty much the same as a standard AR trigger.  If I decide it works, I'll add more material around the lever pin so I've got a stronger print.  I'm also going to reshape and relocate the trigger guard down a bit too so the lever won't protrude into it(and it will print better with less support if the bottom of the trigger guard is inline with the bottom of the magwell). The original trigger spring should reset everything.  Here's how things move when it's fired.  It still probably isn't going to be the world's greatest trigger pull, but it might be good enough.