We stopped at the Copper Mountain RV Park both going to and coming from San Diego from our home in Tucson. A late, 2:30, start occasioned by my 1:00 VA appointment with my knee surgeon (it is finally beginning to improve), made pushing on to San Diego less than an option and Copper Mountain is almost exactly half way between Tucson and San Diego.
Located just south of I-8 at exit 42 it is a large flat (full hook up), park that caters to snowbirds (free cable but no Wifi), particularly Canadians. At $190 a month + metered electricity it's a bargain. The single night rate was $21.35. Lots of activities once the crowd settles in for the winter and the staff was very nice. No pool yet but one is in the planning stages. Admittedly there isn't a lot there but at one third the price of most Yuma Parks it might be worth considering. :C