I like your brand of insanity, um scratch that, sense of style
Just thinking over the box
I know it would look amazingly cool to have both LMS-54K on the front, but be warned you are talking of pushing a little over a kilo of active moving mass with QSC 5050's.
It's gonna make the enclosure buck like a rodeo bull on meth
With this sort of mass and motor power you really should do opposing drivers and PR's to cancel out the forces.
The LMS-54K's are dual 2 ohm, so you would most likely have an 8 ohm nominal load per enclosure, unless you planned on running the RMX 5050's at 8 ohm mono, why not just do one amp like the Series 3 PL 380 that's probably a more cost effective way to go and you'll get 2KW per driver, while eliminating any siginal and/or level matching issues.
I'll go away now