Anyone tried ozone for this? I use it all the time for smells, mold/musty, cigarette, pet odor etc. A lot of car rental companies use it too.
Ozone machine intake should be fresh air, put the output right at the return, and circulate for a couple hours. Obviously, no one should be in the coach during and up to 4 hours after. It's toxic for your lungs until it dissipates.
This is the ozone machine I've used plenty, just hooked up a 4" dryer-vent flex hose to output to direct it where I wanted it. Some hunters even use it to get rid of any biological smells on their clothes.
https://www.amazon.com/Enerzen-Commercial-Industrial-Deodorizer-Sterilizer/dp/B00JAP7388