I never used double wide's but we do use 12' X 55' trailers as mobile offices on job-sites or portable classrooms.
Moderately cared for they have a useful life of 25 years.
To have a one broken down and towed to the dump when we upgrade them it was costing me over 10K between the labor and dump fee.
I started offering them out to contractors, youth organisations or as cabins free....with the stipulation they remove and leave the area they came off of clean of any debris associated from the removal.
Its a win win situation....it keeps the material from going to a landfill, someone gets a very serviceable trailer for just a little sweat equity and it saves my budget the hit.
Its hit or miss, sometimes I could get rid off 10, other times I cant give them away.
Craigslist and word of mouth are easy just make sure whoever says they want it doesn't strip out the sell-able items and leave you with the wood and frame to get rid of.
Good Luck