Andy W – that sounds like a lot of faff when you have a van…far easier to just strap the bike up against the wall with some bungees – the bike is then ready to roll as soon as you stop (and remove the bungees)…like a few have said, no point dismantliing the bike if you own a van as there should be enough space* for the bike to go in complete.
*assuming we are talking Vito sized vehicles and also not meaning full sized penny farthings!
Even my suggestion is too much faff…if I owned a van, the bike would be rolled in and rolled out without any disassembly as that would be a real benefit for owning the van. Saying that, my next vehicle is going to be a Berlingo and I know I can get 3 complete bikes in the rear of one of those so no probs for me…