The 17 digit VIN , should be visible through the windshield's drivers side lower corner.
It will also appear on the vehicle weight sticker , that is placed in various places in RVs , usually in the back of a cupboard or closet , along with a HR production number, and all the tank capacities. There should be a sticker on the coach wall, by the drivers seat that gives tire sizes, rec-commended inflation, and the VIN.
Weight sticker will look like this.