With any "cloth" used to apply a final finish, wash/dry, wash/dry, wash/dry. I have no other opinion other than to say... is it good enough for a 10 yard look? Maybe you're too close to the project. If it's sealed and done... IMHO GO CAMPING. It's not about looking perfect (even brand new from the factory finishes aren't perfect), but is it good enough for you to get out and camp "this season."
In years past, I've camped in tents where holes with sealed with duck tape, my
Scamp exterior was less than stellar clean... but one thing I've always made was memories. Do not delay due to a less than perfect trailer finish. The one thing you can NEVER get back is time....