Hey Dan I have an Air con unit that I am modding also for this purpose. Instead of putting the holes in the side- would it not be just easier to put them in the bottom?. Opinions?..Actually after looking- I am going to rip out the furnace
from my trailer (1976 and I don't trust it) and install the air conditioner right there - I can then utilize the vent hole/grating that already there for one of the vents. Would you say its best to use that for the hot air or cold?.. I'll add a 6" for the other probably in the floor and separate the air flows..