Feedback Buster for larger soundbox

[jazzystel]

Hey guys,

I am a proud owner of a Larrivee OOO-50 acoustic guitar. The guitar has a "B-Band" pickup system installed (after market) which sounds great plugged in. Unfortunately, as it's often the case, I suffer from feedback issues when playing live. I have looked for feedback busters online, but the Larrivee soundbox diameter is larger than the standard size (it's 4.25" or around 10.8cm). I found a couple of companies online that can make custom-sized wooden ones, but I need it to be made of rubber, as I have to cut a small part at the top, in order to be able to access the pickup volume and blend controls which are located just inside the soundbox.

Does anyone know of any suppliers or have any recommendations as to where to find the right item?

Many thanks for your help.
Stelios