Success! Dropped the files into /var/www and used set web-path to ${fog-ip}. In case anyone else has this issue this is my iPXE menu item parameters:
set tftp-path tftp://${fog-ip}/os
set web-path http://${fog-ip}
set pe-path ${web-path}/pm11_winpe
kernel ${tftp-path}/wimboot gui
imgfetch --name BCD ${pe-path}/BCD BCD
imgfetch --name boot.sdi ${pe-path}/boot.sdi boot.sdi
imgfetch --name bootmgr ${pe-path}/bootmgr bootmgr
imgfetch --name boot.wim ${pe-path}/boot.wim boot.wim
boot || goto MENU
B