I have a 2003 Screw and the bottoms of doors, rockers, cab corners are rusting like mad here in Wisco. I know many have the same problem and to get them redone is $3000+ and probably isn't a smart investment. Is there aftermarket moldings to cover this rust up? There are tons of these trucks w/ the same problem...

 

Covering it will only make it worse.

 

Diamond plate vinyl contact sheet might buy you a year or two before the inevitable date with the crusher.

 

ask around and find somebody that works at a local body shop, lots of those guys do work on the side alot cheaper than at the shop.
OR
fix it your self, the parts are fairly inexpensive and it's not that hard to do.
search the forum, there is a thread somewhere that is full of DIY'ers pics and how too's.

here is onehttps://www.f150forum.com/f6/fed-up-rot-231217/
I know there are more and better

 

Yes fixing it yourself is easy. Drill out spot welds and cut the rest, prep new piece, weld in new piece, body work if you want or you can skip if it lined up well enough and looks good. When you're done, you can scuff everything and just use bedliner which cuts time and money quite a bit as well. Materials for both of my rockers added up to like $600 and it was cool to breathe new life into the truck

 

ok, what about the doors, I see the replacement rust door panels are available? How hard are those to line up and weld in?

 

I replaced 2 of my doors and wirebrushed the rust out of the other 2. Some have cut the rust out of the bottoms and welded new pieces in, but with a nice door only costing $50-100 now, I would just replace. Got mine out of a junkyard in Florida on vacation lol