Highly recommended addition to the build
It makes absolute sense to have a centre arm rest/consul. Very useful for stowing those items you need to get to easily and frequently. Not sure why Van's have not included this in the kit. With their facilities it would be very simple to fabricate. Makes getting in and out of the cabin so much easier - a place for the hand to provide support both getting in and out.
We made ours up using stiff cardboard and tape. When it was fabricated to the design we wanted, we took it to a sheet metal shop and they folded it up, didn't cost that much. It easily secures to the floor using existing anchor nuts already installed.