That is not an easy question to answer. In a 68 there are some items that are no longer made and are very valuable. Value is based on what the market will bare on any given day. Are you looking for max profit? Are you looking to help a fellow streamer and make some money? Air Classifieds and e-bay are good places to start. I don't think that the wall panels would be a hot idem, hard to ship and won't fit the next trailer like it fit yours. But you never know.
Do your research. It's hard to predict the out come of an action. Good luck
Thanks for not tossing everything in a landfill.