There have been any number of times I've seen this topic in threads. These high-solvent products are quite penetrating to maximize their effect. Do searches on Gitrot, RotDoctor and Rot Doctor.
I have used RotDoctor on perimeter of new floor only -- under water tank filler & at the water pump, and when replacing floor under the battery compartment and shower. Thing is -- I'm using it on new pieces of filled-core plywood before I install it. I hear you will glue things together so you can never disassemble anything if you use it on an intact trailer. I'm not being too frugal in my restoration but only see reasons to apply this in selected and wetter areas.
Have plenty of fresh air circulating when you use this! The solvent is nasty, nasty, nasty. It may melt anything plastic you use for mixing. Get a cheap fiber brush to apply -- foam brushes get destroyed in an instant. I would use nothing less than a paint spray respirator (rubber nose & mouth mask with organic vapor cartridges). Get some nitrile gloves and wear them. Wash with soap and water right away if you get epoxy on your skin -- some people develop allergy after repeat exposure. It won't be pleasant working around the treated piece for a couple weeks, especially if the trailer is closed up.
Please ask if you have more questions. You may get replies here... If searches produce threads that interest you, Post a Reply there to get feedback from the contributors to those threads. Best of luck!