In March, you'll have your choice of over 100 parks in Yuma and the Foothills (just to the east of Yuma). Many of the parks are modest, but there are some that have more amenities but are more expensive.
We stayed at Shangri La RV Resort out in the Foothills for several years and would recommend it.
Holiday Rambler Navigator DP, Hummer, and Honda VT1100C Shadow