Agreed. But.
I’ll have to talk nicely to someone with a 3D printer (I am not buying a 3D printer!), not that I think that will be an issue. 
I believe the recommendation is to shrink up the RX like this.
After which, I’m anticipating it would be a struggle to feed though here, past the capacitor.
Although it looks like the antenna might just squeeze through if the cap is out of the way.
Also, I’m not relishing the idea of having to disassemble the whole stack to do it. 
And finally, if I do go this route, I won’t be able to have it in the air for tomorrow. 
Edit: Actually, it looks like the RX will go through no problem so I’ll be able to go for a temporary lash-up for now and do the belly mount at a later date when I’m feeling brave enough to take it all apart. 