I have lived in the Phoenix area for the last 19 years and in a MH in Phoenix for the last two years. First it is HOT in the summer, May to Oct. As another poster suggested, get 50 amp service, two AC units and the best insulation you can find, including double pane windows. Buy extra insulation to put in your windows. If you get a MH look for a park where you can face North to keep the sun off the windshield. The second thing is, where are you going to work. Phoenix is very large and the commute can be tough. I think Mesa has the largest number of parks to chose from. There is also light rail in Mesa. If your work site is going to be near light rail, you may want to consider a park near light rail and save the hassle of the commute by car. RVparkreviews.com and Good Sam are two good sources to check out parks. I do not know if you have done a lot of camping, but usually the longer you stay, the lower the rate. We will be moving to Mesa in Aug as I still work. We are going to rent for a year to get the best rate. This is about 1/3 the monthly rate. The downside is we have to pay cash up front for the whole year. You did not say when you plan to move in, but I would suggest making reservations as soon as possible. We started looking at a park in Mesa last month and they had very few spaces left as most have already been reserved by snowbirds for next year.
Good luck with your new unit. I hope you enjoy it as much as we enjoy ours.