Thank you debbiewebbie!
I'm not sure about Escondido, but I seem to recall hearing about something in Fallbrook with horses. I do not know the provider info. I'm sure if you call this number (my son's ABA provider) they could assist you.
Contact: Comprehensive Autism Center (Phone number can only be seen by the question and answer creators)
CAC based in the Temecula area and work through-out San Diego.
My son was able to attend a summer day camp at the YMCA. I had him in the gymnastics camp where I knew he'd be inside most of the time (less likely to run/roam) and it provided much needed physical activity in a fairly controlled environment. Talk to your local YMCA about their programs. They can provide 1:1 if needed and with enough notice.