I wouldn't trust a bike stand, side or centre ones. Even a paddock stand is dodgy unless you have the front of the bike forced up against the front of the van.
I use the Keefy method. Get an old cushion, pillow etc and lean the bike against the van and tie it to the side, two straps per bike is enough one on the centre around the peg or something and the other on the handlebar and pulled to the front of the van, again jamming the front wheel up to the front wall of the van, cable tie around the front brake and put it in gear. Won't budge. Just be careful of how steady your fairing bracket is. Remove your mirrors if you have them. An old mattress has the added benefit of allowing you a comfortable sleep in the van, or even a cat nap at lunch time.
You might be surprised at how much bikes and kit can move on a journey. I have seen bikes damaged by kit not secured and bikes falling over/moving and getting damaged. A 1098 RS arrived in Portimao completed covered in bubble wrap! Think I'd have done the same mind you it looked beautiful.
Thing is though, especially if it's your road bike or a nice paint job, not paying attention when securing could cost you a tiny little scratch which will be very annoying. I used to cover my bike with an old blanket (again use it to sleep with).
The third bike may go in backwards between the two on the walls of the van. Place soft items, kit bags, leathers or tyres between the bikes and strap to both sides of the van. If it's a long wheel base, you will be able to get the third bike behind one of the others, but watch out for the vans wheel arch scratching your belly pan.
Nowadays, I ride my CB500 up the ramp and dump it in the corner - difficult to know how it could be more scratched