Our bus had two A/Cs, and we're doing exactly as you wish... Keeping the front & nixxing the rear. There was no work involved in separating them out, as they were entirely separate systems from the get go. I assume yours is the same, though I don't profess to be an expert. We've pulled one condenser, the associated interior evaporator / blower, and all hoses and wiring for that unit. We've capped the ports of the now-unused compressor and left it in place... theyre both identical, so if the one we're using fails, we could literally just swap the hoses over to the 'spare'.For the one we're keeping we had custom hoses made as we wanted the routing path changed, and also incorporated a bulkhead fitting for the lines instead of just a hole through the floor. Thought that would be expensive but our local shop did it for cheaper than oem replacement hoses would cost, using better and lighter rubber to boot. Before we're ready to recharge the system the amount of oil to add will need to be determined, but that's a job for our trusted shop.
I've got what plants crave.