I quit using hollow core doors after I went out to get a new one to replace my old one.
Upon checking out about 15 doors, in two building supply places, I found that the best one of the bunch was out 1/16". I was using a 36" machinist straight edge for checking. Most of the doors are either cupped or twisted. I also checked out the perma core doors. These were as bad as the hollow core doors. The perma core doors have foam filled core instead of being hollow.
I went to a glass shop that carries salvaged plate glass, and got a piece of 1/2" plate glass that was 3' X 5' for $60.00. I now put this on top of my warped hollow core door, and have a perfectly flat building surface.
I used 3M77 adhesive to glue some ceiling tiles to the glass, but I think I'll get rid of them and go to a piece of sheet rock. The ceiling tiles don't hold pins very well.
You can flip the glass over for cutting out iron on covering, or using your incidence meter and rulers to set up your plane. I use a couple pieces of 1/2" foam on the glass when covering, to protect the plane.
The piece of glass weighs about 80 pounds. The table frame is made of 2X4 material, angle iron, and adjustable legs.

Greg