Newby:When is a tongue too rusty? Need info on used trailer.

Hi,

I found a 1963 Scottsman for sale and it's near the water. It's several hours away from my home. I haven't been to see it because of the distance. From the one picture I have seen of it, the tongue looks rusty. My concern is that it may have spent years within a few miles of the ocean and that leads me to believe that there is a rust issue with the frame/tongue. 

If I were to see it and consider buying it, at what point would the tongue's rust cause me to pull from the sale if everything else seems okay?  Can a new tongue be welded on?

Below is the picture

Note the rust on the tongue...

Thanks