Oh, and I forgot to mention most coaches are NOT 12 volt but 24 volt, they may have a 12 volt supply to run common 12 volt accessories (and even the headlights, if they are sealed beam) but the rest of the coach will be 24 volt, which is good and bad. It means the amperage will be less but things like blower motors are less common, you'll just have to do a little more digging to find them, and most likely be a special order, not in stock at the local truck parts supply.
Another problem that I have wrestled with, when you build a custom system, it is very hard to get the amount of refrigerant correct. I have found no guidance on how to determine amount needed, so have been reduced to trial and error, starting low and working up. The hard part is hitting the right amount without going over, Keep good notes as you go so you know how much you put in when you finely get it right.
I am sure a engineer with a specialty in thermodynamics can mathematically determine the amount, but I've never come across anything that told me how.
Oil capacity is another thing that you have to determine, but IIRC that compressor has a sightglass for the oil level, so you can run the system and keep checking and adding oil until the level in the compressor stays within the safe range. Oil in an A/C system gets carried thruout the whole system, and if you change the volume, more oil may be needed to keep from starving the compressor.