Looks a good job.
The thing that puts me off with going through the floor is the need to disconnect the pole hose from the main hose so you can put the brush away and drive to the next job. Rather than trapping the hose in the van door.
Or can you still do that? But risk the hose dangling under vehicle??
(Asking as this is what troubles my thoughts when deciding what to do, so keen to know how you get on)
I would agree with you, it looks like either a swivel elbow or hard plumb it in and that would give space to move the reel over enough.
Lol its one thing ive now learnt that its not a simple case of amending one thing, it always leads to more work or in my case more hassle (but well worth it)