Clif,
If you go the Samson route - you only need ONE EX30 and then get an EX20 for the other side. The unit is set up for stereo that way. Why waste the money on a second mixer, use longer cables, etc...... ? If all you need to bring is the harmonizer - the SKB 3sp shallow rack MIGHT work. That is one unit that is very shallow, itself. You'd have room for the voiceprism and a power strip too.