[ausev] Air Conditioner for EV

[loopcat]

With the cooler months ahead of us, this may not be the right time for this topic! But, I'm looking for a cost effective way to cool the EV cabin.
Check out this personal ac unit..
http://www.naturalsolutions1.com/amcor2000e.htm
It's 1000 btu, 250w/3amps. which is pretty small. Doing the math, (not my strong subject) 12v x 55amps = 660watts. My 12v system is a Iota-45 and a 55amp aux battery. 
The idea is to mount the unit on the roof and cut holes for the vents and controls. My first concern is efficiency. What kinda drain will this put on the 12v system? The second concern is mounting. Will the ac compressor work laying on its side? I could all ways dismantle the AC unit and reorganize things.
Any thoughts on this idea?
Thanks, Stuart in SA..