Those Carriers do not attach to the drain lines, instead they use a "slinger wheel" to splash the condensate against the hot condenser. This both evaporates the condensate and increases the effectiveness of the condenser. That's the theory, anyway. It might work in Arizona or New Mexico, etc..., but it doesn't work where there is moisture in the air. Like here in Little Rock for instance.
Also, Carrier has exited the RV business so there will be no support at all. I put a Carrier on my Excella three years ago
and it works fine other than the water draining onto the roof. However, I wouldn't do it again even if I could.
Of course, if you are getting a really good deal
, that would be different.