Sounds like it's a land/home resident owned property. You will need to contact a local realtor and have them come up with some comps in your immediated area. There's a tremendous amount of manufactured homes in your area so you shouldn't have any problems coming up with some pretty reliable comps.
I'm a general and manufactured home contractor, dealer, developer and real estate broker in North San Diego county. I pass through Aguanga on my way to Palm Desert frequently. It's a very nice drive and I can't believe what they've done with Manufactured Homes in that area.
You shouldn't have any problems. I wish I was a little closer to you I'd love to list and sell your property. Let me know if you have any difficulty getting some good comps and I'll see what I can pull up on recently sold MH's. But I sure you'll be able to find a cooperative RE broker who is willing to help you out.
Just out of curiousity what is the year, make and size of the home and what do you think you would like to sell it for. I'm just trying to get a feel for values in that area.