Custom Van Conversion

Hello, I am a dog groomer who would like to go mobile. As these vehicles can cost multiple tens of thousands of dollars I am interested in purchasing a high top van and having it outfitted with the necessary equipment. Alas, my conundrum, I have no earthly clue as to who does that type of work. It would need water tanks clean & gray, electrical outlets, generator/inverter, hot water heater, etc. Much like a mobile home. Any suggestions?