Deryk,
I've not finished the condensor side ducting yet, but here is a pic of what I have done:
The fan draws air in the sides and exits the hot air out back. I used a round-to rectangular adaptor (from Home Depot) there on the left. On the outside (round end) a 6" screened dryer exhaust cover (plastic) from HD.
Got to looking and I will have to add another intake on the right side too. I was just going to intake on that left side, but the compressor is on the right intake. The puny load this little TTT is going to put on this 5K BTU unit probably won't require a draft across the compressor, but I will put an intake there too. Just in case. Haven't studied where exactly I draw that air in yet..
To let the heat out I have (but not installed yet) an 8" elbow will be installed and it will shoot the hot air down (through the floor ) and away from the back of the TTT. Where it transitions through the floor, I will make a screened (to keep critters out) cover. The leading (wind side when towing) edge will have a slanted metal flap to keep rain water from the tires from splashing up into the exhaust hole (while towing) and to help shoot the air (while running the AC) toward the back.
You will also have to consider condensed water accumulation in the bottom pan of the AC. The bottom tray will, in humid weather, fill to the brim and slosh out. Mine came with a drain adaptor (pop out black plastic plug, install black plastic drain + drain hose) This will be ran through the floor.
We did test the AC all night (before I closed in the back of the TTT) We sealed the cabin with insulation board and the hot air just blew out the back of the open TTT. Worked great. I didn't have the drain in, so we had some condensate water slash on the floor, but the drain will take car of that.
BTW, I like Parnold's idea for his AC. His he turned it into a poor man's Pet Cool, buy using flexible ducting on the evaporator side. He just hooks the flex tubes up in the window.