Take lots of pictures as you remove items. You will refer to them more than you'd think, even if you're building all new, as we did. Also save most of what you're removing. You may want it for patterns as Roy and Marie said. If you replace the whole subfloor, no worries in the future. A little more time and money now is worth it, we think.
There are many threads on rebuilds. They make good reading and give lots of ideas. We benefited greatly from reading what others had done before us. Our thread is "Little Girl Refurb" on a '72 31ft
Sovereign.
Our trailer had been in Mississippi for many years: the walls were filled with acorns and mouse trails, etc. Very worth it to remove skins and replace insulation as well as rewire.
Good luck and post pictures of your progress. We LOVE pictures here!
Kay