So. Looking at your spec sheet,they're pretty much the same dimensions. Believing you easily possess the ability, after seeing everything you've already done to Fred yourself, why not just chop the top and install a Westfalia style topper? After which, with slightly robust struts installed you could install upside roof mounts for the bikes, handle bars towards the rear against the outside edges and that should give enough room for comfort and never have to disassemble them.
I know, I'm one of those you mentioned in the video and you've already "decided" but you've got do much into Fred and you never get out what you've put in. (Not very stealthy though)