That would be a hassle for sure! I would try what the OP stated in the other thread.

My understanding is:

  1. Set a Static IP for the GL-AR750S itself in the DHCP of the main router.
  2. Open Ports 80 and 22 on the GL-AR750S itself while in Router network mode, before switching to Extender, using Admin Panel → Firewall. There is no security problem because it is all on the LAN.