Gregg Groff
There's no place like 127.0.0.1
1968 Chevy G20 108 panel Now with 454 power!
1965 Chevy G10 panel- OHC Pontiac inline 6
As long as that seat and the seat belts is installed securely and bolted to something substantial, like the ribs or frame of the van, I think it would be fine. It seems like that upholstery company makes them custom for your van. If bolting through thin metal, I would reinforce the mount with a thick washer or flat plate underneath, so the bolt cannot pull through in the event of a crash.
I am also considering the options for child seats, since I have a 9 month old daughter and 6 year old son and would like to take them in the van.