Ouch.
I use 12% as rule of thumb. Tho I have gotten away with 15% once so far.
I do test runs on the game gifting as some games can be coded not to be tradeable outside a region even if its less value.
I've built up a friends list on Steam (from past winners). I use Steams "nickname" to add "zz" and their country "Swiss" before their name. "zz" keeps them sorted to the bottom of my Friends list.

When I want to see if I can gift them the game, I do a dry run of gifting to Swiss and Israeli (and Germany as some games may be banned).

If you can get to the last screen where you have to check the I agree box (after message to friend), its giftable to that country.
If you cannot gift it, Steam will not let you get to the I agree box (last step before you are charged and its sent).

Hopefully these friends dont move to another country.

Thank you for the game! Sorry about the gifting problem. Hopefully you can do a region-specific giveaway for that gift.