you have to remove the papre. Paper comes off really easily. I just get a corner started and it comes right off. I never leave the paper on since it dose come off so easily. any moisture and its done. Packing tape works best to regain some of that regidity the paper had, but at a fraction of the weight.
I have yet to build any of the flight test planes but I have made many planes with my hotwire. Several Funbats, an OV-10 Bronco, and many of my own designs. From what I have seen of their plans it dosent seem like it would hard to make one of their planes without the paper. Though flat wings would need reinforcment.