Bring vpns0 interface up on boot

Hi experts!
I have a working mikrotik wifi router with OpenWRT 23.05.2.
Besides standard wifi router, it also acts as VPN server using ocserv. Due to public IP constraints, I have to use port TCP/443 for both my VPN and my webserver (running on a different machine inside my network). For this reason, I decided to install haproxy on my OpenWRT wifi router and reconfigure various daemons to listen on the loopback interface and the br-lan (my internal interface), so that haproxy can listen on 0.0.0.0:443 (couldn’t make hproxy listen only on the pppoe-wan interface either, because it keeps changing IP).
Right now everything works with the following listening ports setup:
haproxy listening on tcp/0.0.0.0:443
uhttpd listening on tcp/127.0.0.1:8443 tcp/127.0.0.1:8080 tcp/192.168.88.1:8443
tcp/192.168.88.1:8080 (where 192.168.88.1 is the IP of my internal interface br-lan)
ocserv listening on tcp/127.0.0.1:4443 and on udp/0.0.0.0:443 (for DTLS to work).

Haproxy is configured to reverse proxy either to the locally running ocserv, or to the web server running on a different host inside my network, depending on the SNI of the TLS handshake, defaulting to ocserv if SNI is missing.

My struggle now is to make uhttpd listen on the IP of the vpns0 interface of the ocserv, in addition to the IP of the br-lan.
The problem is that the vpns0 interface only comes up if at least one VPN client is connected.
How can I setup the vpns0 interface come up on boot with it’s assigned IP, even if there is no VPN client connected?