Heya, I was moving and missed the thread LOL!
Yes, I have a big frame 4300. I am 6 feet and 200 lbs, and I bought it years ago as a pedal commuter. I think it is a 19 or even 20 inch frame.
all the tips so far are great, you can also try flipping that mount 180 degrees, so the holes are below the engine. I have mine mounted that way. Other than that, it looks like the low profile filter from sick bike parts might work on there? It is going to be close for sure!
All of my build is over here:
New performance bike build - MotoredBikes.com: Motorized Bicycle Forum