Maybe there's more but there's or was a pub in Leichhardt, Sydney, that had installed floor outlets
for their A/Cs as part of renovations. In those days smoking was allowed. These floor outlets pushed
the smoke up and away in ceiling mounted vents. The only public place where smoking was no
longer intrusive and cooling was fine.
Guess floor space in a caravan might be limited, hence rooftop A/Cs.
I have 2 floor standing AC, they are great for cooling & heating. Would have put in wall units (cheaper) but the floor was the simplest solution. Basically the only option.
AC high on the wall will blow air across the room without in general blowing directly on people which is more comfortable.
__________________
Procrastination, mankind's greatest labour saving device!
50L custom fuel rack 6x20W 100/20mppt 4x26Ah gel 28L super insulated fridge TPMS 3 ARB compressors heatsink fan cooled 4L tank aftercooler Air/water OCD cleaning 4 stage car acoustic insulation.
My guess is that it is way less expensive to mount an a/c on the roof. Cut a hole and drop it in. They are made for that job. And as whenarewethere suggests, on the roof is mostly away from dust, dirt and stones. However, some RVers have installed domestic-style inverter split systems to good effect.