Help printing mini-booklet

Hello, I am tasked with printing (digitally) a mini 12-pg booklet 3.5" W x 5" H (final, folded size -- size cannot be adjusted)
We need to produce 5,000 of them.
We have previously done a smaller run of them that we jimmy-rigged to make work. We printed them 2-up (on the spine) on 11x17 paper (as if printing a magazine) and folded + saddle-stitched them via our booklet-maker so that a single staple would go in the middle of each book. So, one center staple per booklet. I have attached a sample spread for reference.
As far as binding goes, we are limited to saddle-stitch, serlox and wiro binding.
I am hoping someone can help me figure out a more effective and less wasteful way of printing these. Any thoughts/ideas would be appreciated!! Thanks.

 

Getting the machine to drop a single staples in a 2up layout was pretty clever.

But the sake of waste - ultimately you can get at least 4up right? How many booklet staplers and staff members do you have at the shop - its labor intensive, but you'll save a ton of clicks and paper. Print the books 4up, collated, and slip sheeted - at 12 pages (3sheets) the book can be hand staples and folded. I wouldn't even worry about the creep on a book this size either.

at a single staple per book, the manual labor may go faster than you think. besides, your jimmy-rigged method would still involve you trimming those 2up layouts - a few at time - for 2500 sets. It may actually be easier to just pop a staple in each book post press - one person can staples - another can fold..

 

Ingenious indeed.
Looks like you could get another set on 11x17 to reduce clicks in half, then cut in half, then run the cut in half sheets through collator bookletmaker to staple 8.5x11 rotated 90 as you did 11x17, and then trim each into two.
That was the absolute limit of our bookletmaker for smallness I think. See if yours can set a staple at 4.25"... might be too small for it if it only goes down to 5.5" real world which might be its limit.