I totally agree: we're having our '62 Tradewind worked on, and I couldn't bring myself to mess with its lines with a rooftop unit.
We've just bit the bullet and gone with an alternative that has been mentioned on the forums occasionally before. Dometic makes A/C units that are intended to cool truck sleeping compartments. They mount under the sleeping bunk and are intended for trucks with auxiliary power units or big battery banks. The idea is to let truckers avoid running their diesels all night.
They make self-contained units as well as units with separate evaporators and condensers. We went for a self-contained one, which is designed to vent downward out of the bottom of the cab (...or trailer). Various posters have suggested that one could use a split unit and mount the external portion on the tongue. This would be quieter inside but arguably less attractive.
The only downside that I can see is cost--they're really, annoyingly expensive. Your mileage may vary on whether this is worth it.
They do not function as heat pumps, but they do have plain-jane electric heat strips built in.
Information on the units is on Dometic's website here:
Dometic Truck Products
We have a "bunkhouse" unit with 4 twin beds in the mid cabin. Our plan is to place it under the streetside bunk, with ducting exiting laterally between the bunks and also forward, under the kitchen sink and into the living area.
I'll let you know how this works out once it's finished. Good luck!