I created a folder in the games folder called night and extracted the models and materials folders from both zip files to that.
I then edited the usermod\gameinfo.txt file placing the Game Night before the call for TF in the searchpaths section of the file.
The models used in SFM are night\Summer_shades.mdl (mask), night\c_hippocrates_burst (machette), items\scout_hair (wig) and night\udayer\scout (custom Undead Scout). The Gmod packs will replace the Summer 2013 Summer shades, the TF\player Scout and any other model that uses the same filename and makes it impossible to use the replaced items in the same movie or poster. To get those items back, just comment out the gameinfo.txt call to the folder you place the GMod packs in."