It might be hard to find a location within 10 miles of downtown Phoenix. There are lots of RV parks in the outlying areas of Tempe and Mesa. Most of those, though, are for semi-perminant (Snowbird) residents who spend the winters there. Most of those folks are gone by the end of April and you may be able to rent a vacant site for a few days.
I am familiar with Venture Out in East Mesa, my wifes folks have a place there. V. O. is one of the few places I know of that provide temporary hook-ups, but I don't know if they are full hook-ups. They have a lot of recreational facilities, but it is probably 30 miles to downtown Phoenix. The freways are close, but the rush hour traffic is a bear.
Sorry I cant be of more help.