Having offered and done this a couple of times for people here, I personally think that I would only want to do it the way I have done it. For the buyer, not for the seller!
honestly, you may not want my opinion!
of your trailer. But the buyer welcomes my honesty...
I would also question, liability for a service for a seller. Could get rather sticky!
I know of some people who took the recomendation of a member who's friend was selling a egg and when I saw the trailer, I sure didn't see, excellent condition! Which is how this person described his friends trailer. Unfortunately, they drove a long way to pick that trailer up. And in my opinion they paid too much and probably could have found a better trailer. Everyone's opinon of what is "excellent condition" is different. That is why I say it could become a sticky situation if a buyer doesn't agree and drives a long way or pays to much!
When I have done it, I take tons of pic's for the buyer to see all the lil details I see. Take ton's of notes and make sure to look over everything.
I don't make a decision for them, I just give them enough nuetral information for them to make their own decision.