Never had a portable unit just the factory ones and I did use a window AC in one old trailer on a trip from Ohio to California
back then 1967 folks said the trip would bounce the compressor around so much it would not work, well work it did and very well
reading the one tube vs two tube portable AC units and thought about a how a car AC works
in the NORMAL position it draws outside air to be cooled in the MAX setting it draws the air from inside the car.
I have found that the AC aeems to work less when the inside or max position is selected after the inside air has been cooled.
I would think the same would be true with a dual hose portable AC
if you could start out drawing air from outside then when the inside gets cool use the inside setting.
Trying to cool down a 100 degree trailer by drawing the inside air only seems to me it would take a lot longer time than outside/ inside one.........
so there you have it get what you want window, roof, or portable all work some better than others
if you are like me what ever you get someone will think you made the wrong choice.............
to them just smile and say "you could be right" while thinking "just go away".
pete