Configuring an Access Point with Wireguard VPN server

I have a GL-MT300N-V2 (Mango). The WAN port is connected to my ISP’s router/gateway.

I’d really like to configure the Mango, which I use as a Wireguard server, so that the WiFi and LAN port were on the same subnet as the WAN and the IP addresses were served from my gateway’s DHCP server.

However when I set the Mango as an access point the VPN menu disappears.

Is what I want to do possible on the Mango or perhaps another device like the Flint?