Are you kidding me? This isn't about you. This is about a potential buyer. You should allow ANYONE to look at your boat and be available for that interaction. A person can be looking at many boats in the market and that takes time and comparison. They may not be willing to give you an offer just to see your boat on a first 1 hour visit. I certainly would never be. They may come thinking they are just looking around the market and end up writing you a check. They also can pass on the word to other potential buyers which believe me happens.
If you can't deal with it, get a broker. This is exactly one of the reasons I don not buy from individual sellers or waste any time with them. They are amateurs They are either too emotionally attached to the boat, don't know how to price the market, think its about themselves, or have no clue about salesmanship.