Truma has some new low profile, German engineered, unit that they've just come out with. The marketing info looks interesting and they can be retrofitted in a non-ducted setup. Plus they have dealers in the US who can do the installation or replacement.
I haven't any experience with their A/C units, but I've been really impressed with my tankless Truma water heater and Truma's service. They also have a tankless water heater/furnace Combi that looks interesting which some RV manufacturers are now using in a few of their models.