score:5
There plenty of dishes in SE Asia that do not use nuts, you won't starve. But as you surmised it could be difficult to determine if nuts were used by smell or sight alone.
First thing you should do when you arrive in each country is to ask someone to write a note about your allergy in the local language. Keep it simple, that you have an allergy to nuts and please do not use nuts when cooking. I came across a website a while back had phrase cards for this sort of thing, but lost track of the url.