I just bought a home here in Florida and my MH has been parked now for over a year. I have NO smells inside. The only thing I do is I have 2 covered roof vents that are left open all the time to allow the heat to escape.
If you have a bad smell in your coach, you need to look at WHY first.
It should NOT smell. If just sitting parked were the cause for smells then each and every RV in the dealership lots in Florida would all smell.
Venting, adding fans etc. is not really solving the problem it's just moving the smell. Just saying find the source of the smell.
One suggestion:
All the p-traps in an RV sitting, "not being used" in hot weather, have to be 'constantly' filled because the water evaporates allowing black and gray tank smell into the inside of the RV.
Amazingly the water in the p-traps evaporates quicker than you'd think. Especially in Florida during the summer months.