How to do custom sorting using unix sort?

I'm using unix sort to sort a comma delimited file with multiple columns. Thus far, this has worked perfectly for sorting the data either numerically or in alphabetical order:

Example file before any sorting:

C,United States,WA,Tacoma,f,1
A,United States,MA,Boston,f,0
B,United States,NY,New York,f,5
A,Canada,QC,Montreal,f,2
A,Bahamas,Bahamas,Nassau,f,2
A,United States,NY,New York,f,1

Sort the file: $ sort -t ',' -k 2,2 -k 3,3 -k 4,4 -k 5,5r -k 6,6nr tmp.csv

Sorted result:

A,Bahamas,Bahamas,Nassau,f,2
A,Canada,QC,Montreal,f,2
A,United States,MA,Boston,f,0
B,United States,NY,New York,f,5
A,United States,NY,New York,f,1
C,United States,WA,Tacoma,f,1

Here is the issue: I want to sort column 2 based on a custom sort, meaning I want United States first, then Canada, then Bahamas:

Desired sort:

A,United States,MA,Boston,f,0
B,United States,NY,New York,f,5
A,United States,NY,New York,f,1
C,United States,WA,Tacoma,f,1
A,Canada,QC,Montreal,f,2
A,Bahamas,Bahamas,Nassau,f,2

Is there some way to pass unix sort a custom sort order that it can then apply? Something like: $ sort -t ',' -k 2,2:'United States, Canada, Bahamas' -k 3,3 -k 4,4 -k 5,5r -k 6,6nr tmp.csv

Thanks!

The other answer and comment answer the question in general, here's how an implementation can look like:

$ cat order
Bahamas,3
Canada,2
United States,1

$ cat data
C,United States,WA,Tacoma,f,1
A,United States,MA,Boston,f,0
B,United States,NY,New York,f,5
A,Canada,QC,Montreal,f,2
A,Bahamas,Bahamas,Nassau,f,2
A,United States,NY,New York,f,1

$ sort -t, -k2 data | join -t, -11 -22 order - | sort -t, -k2n -k4,5 -k6r -k7nr | cut -d, -f 3,1,4-7
A,United States,MA,Boston,f,0
B,United States,NY,New York,f,5
A,United States,NY,New York,f,1
C,United States,WA,Tacoma,f,1
A,Canada,QC,Montreal,f,2
A,Bahamas,Bahamas,Nassau,f,2

You can't do that with sort. At this point, you really should be reaching for awk/perl/your-language-of-choice. You can fudge it, though. You could, for example, use sed to change "United States" to 0, "Canada" to 1 and "Bahamas" to 2, then do a numeric sort against that column, then sed it back. Or change "United States" to "United States,0" etc, sort against the extra column and then discard it.