You're over thinkings and making this far too complicated. The bike is tougher than you allow, and the risk of it hitting you is slight since it's too big to pass between the seats, or even above the seat backs unless it takes flight while still horizontal which is beyond extremely unlikely.
Just do as thousands do, lay the bike flat, right side up so the chain doesn't stain anything, and push it all the way forward so it doesn't slide when you stop (thought the first stop will achieve this without your help). Then just drive with the same care you should use with anything or anybody else in the van.
The only time you need more than minimal common sense is when carrying multiple bikes which can scratch each other or get tangles with pedals in the spokes or otherwise. Then you need to tie them to the sides or use some kind of separators.
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