sealing a trailer floor

[rdsk8ter]

I read somewhere and have been searching again and cant find it. I read people are using roofing emulsion to seal the underside of their trailers has anyone done this? seems to me like it should work but id be worried about a tar smell on hot days. What has everyone used besides just basic undercoating

 

[Ebag333]

Why not just bed line it?

 

[rdsk8ter]

just trying to see cost wise undercoating is a little pricey... and aslo just trying to see if im loosing my mind