Benefits of registration in SD

I’m in Mo (part time) and registered in sd. America’s mailbox in Box Elder. Great service. Primarily as mail forwarding, but have multiple services. Benefit for me is. Plate tags. Our class A and my ford 150. Costs about $440 annual for tags and the bronze plan membership at about $150/yr. ( I don’t need mail forwarded). Plus we paid only 3% sales tax on our bus. It’s 4% now. Big one is this saves us on personal prop (wealth) tax yearly. About $15-1800 a year. They also get my tags and mail them to me. Have a store, nice motel, and rv park if you go there. I also had my Harley Davidson plate there. I love it. You can stay there if you ever need or want to get your SD driver license. Which is recommended. I don’t and it is ok so far.
I’m retired and on the road a lot, so this is the key. I think it’s ok if you’re out of your state more than 6 months. You’d have to check.