I was following this guy, who was using 2" thick foam insulation, then cover with brown paper. He has a complete tutorial on how he does it.
I was planning to build one before I stumbled across FT. He had a neat trick for hinges. Take about 2" of regular string, put some CA on it to make it hard, poke a hole in the foam & insert the string, then hot glue them in.
I use the pink foam for my wings, after a good sanding of the foam i apply Polycrylic to the foam and thin brown paper and then apply the paper to the wing and roll out smooth. Works well and have no issues.
I cover my Styrofoam planes with poster paper and 50-50 white glue. No need to paint if you use the colored paper.
Then I cover the paper with clear laminating film.
All my planes are 1.2m wingspan and weights about 600g with battery
This are a few planes I made this way.