1. Use a wireless and walk out into the audience to see how it sounds with the whole band playing. Standing in front of your amp with nobody else playing tells you nothing.
2. Write down the settings that worked in that room to save time next time.
3. A dirt pedal like the rat can take a lot of the low end punch (eq frequencies below about 200Hz) out of your signal. If it has a blend knob that's great, you can blend some of that bass-rich clean signal back in. If not, see if you like the drive on the sansamp. Mine (sansamp para driver di) has a blend control, maybe all the sansamps do, I don't know.