SB defence range in playing 3handed

[yourface]

edit: 1/2 blind structure

button is a LAG. he is raising the button about 65% of the time. he is mediocre postflop; peels too light, calls down too light, gives too much action with his hands

BB is the same kind of guy. he's going to be playing around 70% of hands.
edit: he will cap the top 10% of hands

what do you think is a good range for defending your SB playing 3 handed? how did you make this range up?
are you always 3betting?