Residency and voters rights in South Dakota

In Montana small towns have the ability to enact a local resort tax. The money stays in the community and can be used for a variety of local projects. A town where I owned a park put such a tax on the ballot. The town was a major tourist town with over 700,000 vehicles visitors each season. The tax is assessed on lodging, including RV stays less than 30 days. The community population is less than 800 and the eligible voter count less than 400. Those visitors put a huge strain on water, sewer, roadways and other visitor services. Heck, over $30,000 a year was spent keeping a public restroom facility clean and supplied using mostly volunteer labor. Prior to the vote it was discovered a local non profit entity that was opposed to the tax was encouraging out of town members to change their address to that non profits location which they could then use to register to vote against the proposal. In the end it was revealed that address had 48 registered voters even though it had no lodging facilities at all. The tax ultimately passed, but the vote was much closer than projected, likely due to those extra 48 votes. The county registrar office subsequently put out guidance that falsely claiming residency to vote is fraud and a crime.