Mastering 2 or more separate tracks that will play together

[Orion Satori]

Let's say I'm mastering multiple tracks that I will use simultaneously as backing tracks on stage. Should I master them all so that each track's Peak/RMS levels are loud as they normally would be, or do I want to master them so that the sum of their total volume together is around the level it would be if they were mixed into one and then mastered? I'm guessing I would master them all as if they were individual songs, and then, I just don't play my live master volume as loud. Thanks in advance.

[3dot...]

master them so they would sound good together.. and sound good on loudspeakers..
volume is secondary if it's going to PA(can always be easily adjusted afterwards..)
ALTHOUGH...the generalrule is to try and use the full volume resolution of the file