This is harder than you will like...
1. Route tracks to a master bus
2. Send to master 2 left and pan left
3. Send to master 2 right and pan right
4. Set master 2 left and right buses to mono interleave and add compressors
5. Route both to master 3, panned appropriately
Different from using the sends with panning, you could use channel tools in master 2 mono buses to constrain each to appropriate signal for compression.
You could also do Multiband limiting independently.