Given that this order you desire is unfortunately not alphabetical (although that wouldn’t be very scaleable… but it would be handy). You might make life easier on yourself by adding another custom field called (say) “display_order”. Then add the numbers 1,2 and 3 to that field, and then query the post type ordering by these values.
As far as I can see, it’s that or running three separate queries to retrieve the three “levels” of board. Or some madder idea of retrieving them via one query into an array, and ordering that array as you require.