I have one of these, and it works really well.
http://cirrus.tlc-direct.co.uk/Produ...AC12000DB.html
(The external unit is actually white (well mine is)

Can you disconnect the external unit from the internal? I already have a
duct through the wall for the vent on a monobloc unit, and I'd like
to pass the hose through that...

Yes, they have self sealing connections, just undo them, keeping the pipes
straight, and you should be just fine :-)

The manual for it is here
http://cirrus.tlc-direct.co.uk/Techn...PAC12000DB.pdf
Have a look on page 7

Sparks...