I use a Mesa Boogie Stereo 20/20. A single rack space and way lighter than the RT2/50 or the more powerful Mesa Boogie rack amps.
The 20/20 will make your ears bleed. Any gigs we play that need more power, we team up with a sound company that uses some nice mics on my cabs. So my rig is reduced to being my on-stage monitor.
So my rig fits in a 6U rack box: RM4 (2 spaces), DigiTech GSP-2101 (2 spaces - yes the 2101 not the 1101), a Monster Power Pro 2500 (1 space) and the Boogie 20/20 (1 space). Easy-peasy setup and tear-down. Eat yer heart out, Marshall stacks.