I think everything can be loud at once.
It's having everything louder than everything else at the same time that's tricky. Doing things backwards as usual, I measure the average loudness of the tracks AFTER MIXING haha rather than leveling before mixing.
These are the numbers I'm getting on the latest mist of a different track from the concert...
I'm using the RME EBU Average Loudness over time meter...
The guitar is betwen -19 dB.
The Keys are around -21.5 dB.
The bass is around -14.3 dB.
The drumz are around -20.1 dB.
The vocals are around -19 dB (only measured during singing).
I solo'd the tracks and played them through the meter for the 5 minute tune.