Exactly!
You can ask the same question to Nick Mutton and he'll say the same thing.
Boa Constrictor locality animals are not uncommon here in the US. Carpet locality animals are very much a rarity here by comparison.
You likely have a mix and that's OK.
I have a coastal, mutt myself and have asked the same question. Nick Mutton emailed me back after looking at the photos I sent him way back when and told me there was no way to tell.
I love my mixy-mutt and am plenty happy with her. She was a very inexpensive pickup from an expo.