Masquerade inbound TCP traffic

Hi there
I have a special solution where i have RouterOS on the inside of my system.

i have the follwing:

External firewall only being able to dest-nat
One Ethernet IP: 10.0.0.10
OpenVPN client @ 10.0.0.62

I need to masquerade incoming (dest-natted) traffic on port 20079 to the OpenVPN client so that it appears it is coming from the Ethernet IP (10.0.0.10)

Like this:

TCP 20070 from outside Dest-Nat to 10.0.0.10 → Masquerade to 10.0.0.62

I cannot des-nat directly to 10.0.0.62 because tunnel isn’t it’s default route and it can’t be changed. I only have one interface on RouterOS

Anyone have any good ideas?

Regards

Henrik