Can I make this extension cab work?

[Pseudosam74]

I'm using an RT2/50 with one of the Randall XL cabs.
The cab can run 4 or 16 ohms mono, or 8 Ohms stereo.
I have a lead on another Randall cab that I'd like to use as extension, but it's 8 ohms only (mono).
How can I properly and safely use these two cabs together while running the RT2/50 in mono/switching mode?

Can I use the second main out as an extended out and have two different impedence settings for the two main outs?

 

[m0jo]

Each channel has it's own output transformer and ohmage switch.

So in stereo mode you could use one cab for one channel.

The following bit is from memory, I might be wrong
I believe that you can also use one cab per channel in switching mode, the one not selected will be silent.
So if you've chosen channel A, only cab A will give sound.

If you want both cabs at the same time, you should use the channel 1 outputs only, which is a problem since you have a mismatch.
You could rewire the 8 ohm cab ... it's not hard if you have some soldering experience.