We were SD residents but owned property in CO and spent a couple of months in the spring and in the fall here. We stayed at an RV site on our property (a 3000 tree commercial peach orchard we inherited). We did that for several years with no problems. We did have to pay CO non-resident taxes on the income from the property.
I can't find an exact cite but we were told that if you are in CO for more than 90 continuous days you must become a resident. This site does reference the 90 days
HEREIf you become legal residents of SD and divorce yourself of most connections (except for owning property) and don't spend too much continuous time in the state it would seem that you should be okay.
There is some good info about what constitutes a legal domicile
HEREIn 2004 after we had started full timing in 2002, we investigated becoming residents of CO but found the cost to register our motor home and car was very expensive - about $1600 more per year than in SD. After ten years though the cost has decreased to the point that it is about the same here as in SD.