New mini heat pump in my Transit

Hello to all this is my first post, my wife and I just purchased a Transit 350 Diesel passenger van which will be transformed into a all purpose camper rv, we've owned a 84 vanagon for years which I installed a Subaru wrx motor in but still lacked some of the modern desires of the Ford Transit so here we go on the Transit camper build. First thing was to purchased golf cart batteries which would give us at least 400 amp hour feeding the 1500W pure signwave inverter which will power many of the 120v comforts of home, the biggest challenge was air conditioning and the heat, Ive researched MANY different systems but found this unit and its amazing! Total size is 9" high, 14" long by 7" deep. It comes in AC or AC/ DC versions and when running on DC draws a little over 20 amps. It does require an external water radiator in order to dissipate the heat from the condenser which I will run water line to the roof and install a small radiator or this may change as my build goes along but for now that is my thought. Also its rated at 4200 BTU but the owner of the company who designed it said it pumps over 5000 BTU but hes keeping the underrating..

Here is is site and he also has a couple youtube videos.
http://minihvac.com/