Hemet Riverside County adding a older mobile home to land permits

Hello I have a 1 acre land in Hemet on a street where every property on there has a mobile home on it except mine. Mine has a trailer 2 bed 2 bath with permits from the 60s. I cannot refi. So im planning to put a older manufacture home with permanent foundation so i can refi. I spoke to county of Riverside earlier this year about it and they said its possible. Is this complicated to do? i see older homes from 70s about 1100 sq ft that need work for about 20k. I want to be more prepared before i go in and talk to city, i call them and they dont want to talk over the phone it seems maybe there really busy. What is needed for this to happen?