Question on 2003 Ford e350 super duty van

[Daniel6610]

Let me know if this is the wrong place for this.

We bought a 2003 Ford e350 super duty extended van to semi convert for camping. I got all the old flooring out but I am not sure what to use now. It is not a high top van, just a standard height, so we don’t want a thick floor. Would it be alright to just glue plywood to the floor? Or should we put some kind of insulator/vapor barrier under it? What kind/thickness plywood should we use? We want to put think stick on flooring on top of it. We are just planning on building a bed/storage in the back and maybe a counter/storage in the front part. No extreme makeover for this vehicle...

Thanks in advance...