Welcome to the forum.
Yes, Visone is a good place to check along with Colaw as I believe that those are the biggest RV salvage yards(?). Others may be able suggest other salvage yards to check too.
I did a quick search and I see that both Visone and Colaw have 2000, 2001, 2002 Tradewinds listed on their website but I'm not sure how up-to-date they keep their inventory list as it pertains to their website. But giving them both a call would confirm one way or the other.
Also, I'm not certain but others more familiar with National RVs could advise, if a 2000 model is identical in body parts, etc. as a 2001. 2002, etc. ...in other words, maybe a storage door that fits a 2002 Tradewinds would work for your 2000. etc. I'm going to guess that the 2000-2002 body parts would be the same but I'm not sure.
Here's the quick search but you might re-check both websites and others to see inventory for comparison purposes ...and of course, call both and other places too:
Visone 2000 National Tradewinds - three shown
Visone 2001 National Tradewinds - three shown
Visone 2002 National Trandwinds - six shown
Colaw 2000 National Tradewinds
Colaw 2001 National Tradewinds
Colaw 2001 National Tradewinds
Colaw 2001 National Tradewinds
Colaw 2001 National Tradewinds
Colaw 2002 National Tradewinds
Colaw 1999 National Tradewinds
eta: those Visone links evidently only show for a limited period of time and I see that they have expired so just use the search bar on their website to see those units I referenced by the links posted.