The cover for the airbox on this Honda generator hinges open to the left, but the frame rail is directly in front. The airbox is also bolted to the engine from inside (behind the filter).
I've throughly looked over this and there is no way to open that airbox unless you unbolt the engine from the frame, or perhaps modify the lid hinges with a saw so it doesn't have to swing as far to come off.
Honestly, I might just do that.
For now it's mostly just being ignored. Occasionally we jamb a compressed air nozzle in the cracks.
It's a generator, it doesn't collect nearly as much dust as the other tools (like a plate tamper for example); and it really doesn't go out very often or very long (rental).