MTS

So the finished bed runner will be 26x108, right? Maybe less than 108"?
Same material front and back?

I would approach it another way.

I would just hack off (cut or rip) one larger 56"-ish x WOF (108") piece, which doesn't have to be a perfect cut.
The remaining ~ 17" will be more than enough for the binding, if you were planning on using the same fabric.


Take a larger piece of batting than needed, say 30" x 112" (piece it if needed).

Press the fabric in half, insert the batting inside so it's flush with the fold, and quilt as desired.
You can use the spray baste or dabs of elmer's washable glue here and there to keep the batting in place.
If it's encased in the fabric falafel, I doubt it's going to shift much.

It's will be much easier to stabilize and trim a finished quilt than all those pieces of fabric (when the quilted bed runner would have to be trimmed anyway).

It won't be nearly as flimsy.

When trimming up the finished quilt, you can use just your rulers , or draw (chalk, sharpie, or soap) lines and then cut.

If you're really intimidated by the size, get someone to help and snap a chalk line (I did that once back in the day on an early kingsize quilt) where you want to cut.