Made of old pallet wood. so was the cost of my time and some screws.
I’v snice stuck a hinged arm to the bace that braces against the front seat leg and I use a tie down strap to pull it tight to the same leg.
Bike gets velcro’d in to the rack around the wheel. If I can be bothered I use another strap from frame to side of the van.
Nowhere near as fancy as some solutions above – but I pop it in / take it out in a minute, (or can chuck it outside the van to make space if we’re away – it’s unlikely to be nikced!). It’s a lot more secure than just a strap to the side of the van and it keeps dirty bikes from leaning on other kit etc.
Just another option for you.
Si