2007 isn't all that old.
I would suggest that you simply sell the entire trailer AS IS disclosing that it DOES have a lot of water damage.
This way you don't have to find ways to "dispose" of A LOT OF unwanted materials. The cost of disposing of all the old wood and non recyclable materials will easily eat up any profits you would get by parting it out.
Offer it for $3000 and go down to $2500 and someone will get a pretty good deal and you don't have to figure out how to get rid of all the wood and such.
Like I stated though, DISCLOSE the fact that you KNOW it has water damage.
My current TT was SEVERELY water damaged when I bought it. I knowingly bought it that way although I paid under $1000 for it. But keep in mind that when I bought it it was over 20 yrs old at that time.
I removed all the siding and roofing, gutted the interior then resided, reroofed and rebuilt the interior the way I wanted it.
There ARE adventure seekers out there that do not mind a bit of hard work to take a diamond in the ruff and make it a gem.
Put it craigslist.org, it is FREE and you can post 4 pictures also. You will need to relist it every few days to bring it back to the top of the list but hey, FREE is good.