GO ON YOU CP FIND THE CLUBS WHERER U LIVE AT GO TO THEM ASK THEM WHAT U WANT TO KNOW

I have built several planes on a 30" x6' folding table with ceiling tile on top, all come out straight and flew great. So yeah, I think your over thinking it also on the flatness.

A 30 inch solid core door can be bought at one of the mega lumber yards for about $50-60. One of those with a piece of drywall on top should be fine. The LT-40 snaps together for the majority of the construction. You will love that plane.