Good job @Cuppa. You have ample room. My whole battery and DC-DC assembly is where your catch can ended up.
I only have one vacuum tank, at the spot where you have two. So thats roughly where mine will end up.

While we're at it ... Do you know / Have you measured the barb sizes needed exactly? I see you've ordered 25mm -> 16mm reducers.
Is the hose bar at motor end AND the air intake hose end the same? 16mm ?
I'm a little confused what size hoses are needed exactly.