Classical Guitar Soundhole Cover?

Does anyone know of a commercially available soundhole cover small enough for a LaPatrie classical guitar?

A fairly exhaustive search of the web has turned up dozens of covers for larger holes, but nothing for a classical guitar. I could make my own, but the convenience of buying one saves me time and effort. I use my classical in church, amplified through a Traynor AM150T (with a notch filter). I've tried a modified (it was too big) Planet Waves O Port but it was a tone suck (both acoustically and plugged in), and though it did significantly lower the frequency of the feedback, it didn't actually eliminate the problem.

Thanks in advance for any and all advice.

Peace, Mike,