Can an elderly couple get a Las Vegas style wedding that is to maintain good public image, but not financially binding if they split up later?

A marriage is a marriage is a marriage, whether it is in Las Vegas or anywhere else, and there are financial consequences in the event of a divorce, so what you really need is a pre-nuptual agreement. The thing about a pre-nuptual agreement is that it is absolutely impossible to get married without one. Think about it. If you don't come up with your own agreement about what happens in the event of a divorce, you're stuck with whatever the good people of the state where you eventually get divorced say should happen in those circumstances. In other words, there are statutes on the books in every state that determine how property is to be distributed in the event of a divorce. There can be significant variations among them too. There's a world of difference between what happens in a community property state versus other states. And there's no guaranty that a divorce will happen in any particular state. Your spouse can go shopping for the friendliest jurisdiction where the most favorable treatment is most likely. So you're either going to get the pre-nuptual agreement provided by the state or a pre-nuptual agreement that you and your spouse agree to in advance. Which would you rather have? People have very mistaken views about pre-nuptual agreements. They're not a tool for the wealthier spouse to cheat the spouse without means. Pre-nuptual agreements are much more difficult to enforce if one spouse is treated unfairly. They are a fantastic tool to ensure that property is distributed fairly in the event that things don't work out as everyone hopes.  Much better to figure that out at the beginning when good feelings prevail rather than later when things have turned ugly.