The only problem with that plan is, with exotic pheasants, when they get sick.......that's usually the end of them. Before wasting a beautiful bird, it's best to be prepared to properly house them. Not to just get them because you want them.
All the advise previously given on proper housing is spot on, from years of experience in keeping the various breeds. Best to heed it, The humidity may play a part in pen to pen transmission, but when in the same enclosure, they are in each others poo, therefore it would be a direct transmission of disease.
Personally, I have a pair of boots for each type of enclosure, 1 for the peafowl, 1 for the pheasants, turkeys, waterfowl, bantams....As each type may be carriers of one thing the other is susceptible to.
Always best to be safe than sorry....