Seems a bit high to me with the needed repairs. I don't consider the table to be a big deal but the mold and canvas are a concern. I can't really comment on the frame.
For comparison, I paid $3200 for my 1970 Campster
in August. It is escentially the same trailer. The frame is clean, canvas is perfect, door is good, no repairs are needed. On mine, the propane
has been removed and a solar panel
added and the tongue was extended by 2 feet. I don't know the full history but I know it was garaged for the last 8 years.
There is another Campster for sale
on the forum for even less than I paid. It's not in as good as shape as mine (I've seen it) but sounds better than this one.
So, while the comparison is not perfect, hopefully this gives you some thoughts for negotiations.
Good luck and have fun.
1970 Trails West Campster
2008 Honda Ridgeline