One group of Hopewell people in Hamilton County, Ohio, collected and then disposed of 48,000 pearls in an artifact deposit that was later covered by the Turner mound. Archaeologists excavating the Hopewell site in the 1880s found 100,000 pearls. Some were inset into bear canine-tooth buttons or applied to copper ornaments. Most had been drilled, perhaps with a hot copper wire, and strung as necklaces or sewn onto clothing.
Cement: Roper writes, " In the Book of Helaman (3:7, 9 & 11) it is stated that those people who went to the land northward were expert in the working of cement. This activity took place about 46 B.C. according to the date given in the above Book. Cement was extensively used in Mesoamerica around this time. The earliest known sample dates to about the First Century B.C.19 One of the most famous sites for this early cement is at Teotihuacan (located about 30 miles northeast of Mexico City). Margain commented that, “Concrete is encountered in all Teotihuacan constructions of every epoch.”20"
Of course, Helaman refers to a temporary exception to normal Nephite building materials; they had to use cement because they'd cut or burned the trees, and it took a long time for the trees to regrow. That's about as opposite of Mesoamerica as one can get. First, as Roper's own quotation demonstrates, they used concrete everywhere during "every epoch." Second, the idea that trees take a long time to grow in Mesoamerica is just a little bit at odds with the rapid growth of dense jungles. Trees grow slowly in northern climates that have short summers, not near the equator (or within the tropics) where there is abundant sun all year round. The North Americans knew something about cement; e.g., Joseph Smith reported that the stone box containing the plates was built with cement. Many of the mounds in North America were covered with cement, as were the walls around the cities.
Culture: Roper writes, "Archaeological studies have shown that peoples in Mesoamerica during Book of Mormon times had: A complex society, many large and complex buildings, fortifications, a high degree of art, a good understanding of astronomy, a highly accurate calendar, a sophisticated knowledge of agriculture and husbandry and more.24 This type of an advanced civilization at the time is not known anywhere else in North America north of Mesoamerica. Certainly the region around the present-day New York state does not contain such evidences. In fact studies show that the people living there for several thousand years until the time of European settlers moved in were tribal hunter-gatherers."
I'll assume Roper is writing out of ignorance, maybe because he believed Sorenson's list of problems with North America, but everything he wrote here applies equally to the Hopewell civilization; i.e., "A complex society, many large and complex buildings, fortifications, a high degree of art, a good understanding of astronomy, a highly accurate calendar, a sophisticated knowledge of agriculture and husbandry and more." It's a little surprising to see this ignorance of Hopewell culture persist, but when ignorance is bliss...
Climate: Roper writes, "What little has been indicated about climate in the Book of Mormon lands implies year-around warm and mild conditions." He mentions the fevers from Alma 46:40--as if he didn't know malaria was common in the Midwest. Even in the 1840s, the Saints in Nauvoo suffered from exactly the maladies described in the Book of Mormon. The North American highways were truly "cast up" as the Book of Mormon describes.
So all eight of Roper's reasons point to North America at least as much as Mesoamerica, and in most cases, are a better fit in North America. But then when he gets into his discussion of animals, he has to acknowledge that the examples of Book of Mormon animals are mostly in North America. He simply assumes they might have migrated down to Mesoamerica! (He even goes so far as to suggest the tapir is an elephant.) He explains the lack of evidence in Mesoamerica this way: "A reason more is not known about the horse and other extinct animals in Mesoamerica is that their remains are much less likely to be preserved and also less likely to be found when they are. In general organisms do not preserve well after death in subtropical and tropical environments."
That's true of all animals everywhere, of course; otherwise, the ground would be littered with the remains of the millions of animals that die each year. But since there is more evidence of the necessary animals in North America, and since all of Roper's eight points also fit North America better, and since the Times and Seasons articles (the only reason we even look at Mesoamerica) weren't written by Joseph Smith, why not just abandon the Mesoamerican theory and focus on North America?