Sealing the Trailer

This is the greatest place for information. I have read till my head hurts. But I have a questions about sealing of the trailer.
I have read that most people use the black rooding tar on the bottom of the TD. So in building the floor would this be the process to take:
1. Build out of treated or regular lumber.
2. Do I put CPES on at this point or goto.....
3. Coat bottom with Black roofing tar.
On the top and sides the end result I am shooting for is painted top and part way down the sides. Then the rest just clear sealer. So the next question is sealing and painting.
1. Build TD
2. Coat everything outside with CPES or Epoxy?
3. Then start priming and painting.
4. Then coat everything with a spar varnish.
Thanks again for all the info on this site.
I have read that most people use the black rooding tar on the bottom of the TD. So in building the floor would this be the process to take:
1. Build out of treated or regular lumber.
2. Do I put CPES on at this point or goto.....
3. Coat bottom with Black roofing tar.
On the top and sides the end result I am shooting for is painted top and part way down the sides. Then the rest just clear sealer. So the next question is sealing and painting.
1. Build TD
2. Coat everything outside with CPES or Epoxy?
3. Then start priming and painting.
4. Then coat everything with a spar varnish.
Thanks again for all the info on this site.