I solved the problem.
First I created a Single Gateway pointing to remote Tunnel IP of corp (4.3.2.1).
Then I setup 1:1 NAT with external IP being local Tunnel endpoint (2.3.4.5/32) and internal IP pointing to my proxy (172.18.70.11/32). NAT Reflection enabled.
Then I created a Firewall rule on IPSec Interface allowing traffic from remote tunnel IP (4.3.2.1) to my internal proxy IP (172.18.70.11/32).
What did the trick was going to advanced Options for this firewall rule and set the "reply_to" option to the Gateway created in the first step.
And I had to remove other rules that were applied to this traffic to make sure my new created rule is actually applied so the gateway rule was active.
First I created a Single Gateway pointing to remote Tunnel IP of corp (4.3.2.1).
Then I setup 1:1 NAT with external IP being local Tunnel endpoint (2.3.4.5/32) and internal IP pointing to my proxy (172.18.70.11/32). NAT Reflection enabled.
Then I created a Firewall rule on IPSec Interface allowing traffic from remote tunnel IP (4.3.2.1) to my internal proxy IP (172.18.70.11/32).
What did the trick was going to advanced Options for this firewall rule and set the "reply_to" option to the Gateway created in the first step.
And I had to remove other rules that were applied to this traffic to make sure my new created rule is actually applied so the gateway rule was active.
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