That's a good looking perch fly! I'd fish it.
I've never tied any fly with mono. I wonder why you would you need to? I used to tie several hundred pike flies a season, and got them all chewed up fishing and guiding in Canadian waters that were just full of pike. I mean, dozens of hook ups daily, big toothy ones. I used single strand floss to tie with, and super-glued the head, butt, and any other tie-down point that was exposed. The materials on the fly itself would get chewed up before the thread wraps would get mangled or come loose. I now do the same thing on my tarpon flies.
Kevlar is an option, like you mentioned. A cheaper alternative might be a small filler spool of small diameter Spectra braided line such as Power Pro. I've tied jigs and other "lures" with it.
But with fly durability, super glue is your friend, at least it is for me. It really holds large bulky flies together well.