Chuck, I applaud you for trying to get this trailer looking great.  Cleaning tent trailers and hybrids is really important as a clean canvas will last longer and remain water proof PROVIDED you don't use some kind of cleaner that will damage it.
The rubbing alcohol sounds like a good option but I would caution you to be very careful.  Check with the manufacturer and see what they say.  If you can't do that carefully test a small patch before you go crazy.  This is all common sense so I apologize if I somehow insulted you.  Sometimes good intentions do go astray.
We had a hybrid for about 5 years and still am amazed at how open and spacious it was.  I did get some gizmos but only used them when we camped in very cold conditions. My bunk ends were clean when we sold it.  I used basic car wash soap with a soft brush.  That worked for me.  I did remove some very small spots of tree sap using a bug and tar remover formulated for car finishes.