STEP 1 (AUTOMATIC)
Blocker should have done this for you already. If not, launch Safari then click Safari from the menu bar and select Settings....
STEP 2
Ensure that Allow in Private Browsing is checked.
You can disable website statistics collection for private windows by going to Settings > Statistics in Blocker.
STEP 3
Click the Profiles tab at the top. Then, for each profile that has extensions settings, ensure that Cold Turkey is checked.