Congratulation on your 25th anniversary! We had been married perhaps 17 years when we 'took the plunge' (so to speak) and signed up to go to Club Orient. Some thoughts...
1. Orient Beach is 1.25 miles of white sand, most of which is not clothing optional. It is a lovely beach with nice places to eat and some water sports. However, if you want to experience and enjoy being naked, you want to be at the South end of the beach where Club Orient is located. There is a parking area, Club O welcomes (at least historically has welcomed) day visitors, ask about renting chairs under the yellow umbrellas, towels and so on.
2. Check out the Club Orient website. The property has many nice features including the Papagayo restaurant, the small but well stocked general store. The general store has everything you might need and forgot to bring. Also souvenirs.
3. Maybe pertinent to your thoughts, the public nudity at Club O is absolutely G-rated. You will see nothing that you would not see at a church social held lakeside, except that those who are on property are (mostly) naked. The interesting thing is how quickly you will feel 'normal' being naked when everyone else is. Mrs. FL had a variety of concerns the first time we went, brought two swimsuits with her. First day, she put one on. It came off ten minutes later. As she put it, "The swimsuit felt weird and out of place." Translation: as soon as the cultural expectation of being 'covered' is rescinded, it's just more comfortable not putting up with the textile nuisances.
4. The beach is operationally a French beach, meaning it is public. There are a fair number of people who walk to the south end to gawk. It is worse on days when the big cruise ships are in port. They tend to walk at water's edge. Pay them no mind. You two will be no more than a pair of a couple of hundred naked people just enjoying the sun.
5. Sunscreen. More sunscreen. Really.
Here is what happened to us. We followed our original plan and went off property one night for dinner. It was wonderful going to Grand Case. Only problem, we had to get dressed, go off property, and then return. By the next day, "sand gravity" has set in, it was much easier deciding "what not to wear" to go to Papagayo. Life was just easier being around people genuinely comfortable in their own skins, figuratively and literally.
The downside of all of this is pretty simple. There is chance that you will decide "tried it, not for us". But there is a far greater chance that you will decide that in warm weather, especially at resorts and by the water, clothes have little practical value and are more of a nuisance than anything else. The downside, then, is a reasonably high risk that you will develop a strong preference for clothing-optional destinations and the people who choose them.