Thanks for the input guys.
@mrjmt – yeah I have the extension option as a potential back up, cheers.
@hot_fiat – thanks for the easy base link. That is something similar to what I intent to make!
@jef – agree on your points, it is high up for sure! Unfortunately for a whole multitude of reasons a towbar is not going to work on my van!
@welshfarmer – sounds like we are on the same wavelength! I had thought about the side on vs front on forces. Was thinking of using a couple of the small Atera bike to bike holders – one connected to the frame of the bike rack secured to van on one end and to bike 1 at the other end? Then if carrying a second bike a second bike to bike between them? https://www.roofbox.co.uk/scripts/rbvehsel4_tab.php?29037
Side note – saw some really cool front bike carriers for Defenders on one of the NZ uplift service pages, looked good.