Managed to source a proper VM euro module with the inline isolator. There's no photos online of what it looks like, so for anyone else wondering, it comes pre-fitted with a very thin cable out of the back, and then a female f-connector after about 8" of wire. There's a long bit of sheathing you can move that covers the connection once it's screwed together.
Got the whole lot installed and it's looking much neater, and signal/power levels are virtually unchanged. Result!
Photo (excuse the render missing from half of the wall, doing all this re-cabling work in preparation for re-plastering this week):
